Sample records for alaskan yukon river

  1. Influence of the Yukon River on the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, K.; Mcroy, C. P.

    1986-01-01

    The relationships between the discharge of the Yukon River to the currents and biological productivity in the northern Bering Sea were studied. Specific objectives were: to develop thermal, sediment, and chlorophyll surface maps using Thematic Mapper (TM) data of the discharge of the Yukon River and the Alaskan Coastal Current during the ice free season; to develop a historical model of the distribution of the Yukon River discharge and the Alaskan Coastal Current using LANDSAT Multispectral band scanner (MSS) and NOAA satellite imagery; and to use high resolution TM data to define the surface dynamics of the front between the Alaskan Coastal Current and the Bering Shelf/Anadyr Current. LANDSAT MSS, TM, and Advanced Very High Resolution Radiometer (AVHRR) data were recorded during the 1985 ice free period. The data coincided with shipboard measurements acquired by Inner Shelf Transfer and Recycling (ISTAR) project scientists. An integrated model of the distribution of turbid water discharged from the Yukon River was compiled. A similar model is also being compiled for the Alaskan Coastal and Bering Shelf/Anadyr water masses based on their thermal expressions seen on AVHRR imagery.

  2. Spatial variability and landscape controls of near-surface permafrost within the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Rose, Joshua R.; Rigge, Matthew; Walvoord, Michelle Ann

    2014-01-01

    The distribution of permafrost is important to understand because of permafrost's influence on high-latitude ecosystem structure and functions. Moreover, near-surface (defined here as within 1 m of the Earth's surface) permafrost is particularly susceptible to a warming climate and is generally poorly mapped at regional scales. Subsequently, our objectives were to (1) develop the first-known binary and probabilistic maps of near-surface permafrost distributions at a 30 m resolution in the Alaskan Yukon River Basin by employing decision tree models, field measurements, and remotely sensed and mapped biophysical data; (2) evaluate the relative contribution of 39 biophysical variables used in the models; and (3) assess the landscape-scale factors controlling spatial variations in permafrost extent. Areas estimated to be present and absent of near-surface permafrost occupy approximately 46% and 45% of the Alaskan Yukon River Basin, respectively; masked areas (e.g., water and developed) account for the remaining 9% of the landscape. Strong predictors of near-surface permafrost include climatic indices, land cover, topography, and Landsat 7 Enhanced Thematic Mapper Plus spectral information. Our quantitative modeling approach enabled us to generate regional near-surface permafrost maps and provide essential information for resource managers and modelers to better understand near-surface permafrost distribution and how it relates to environmental factors and conditions.

  3. Influence of the Yukon River on the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, Kenneson G.; Mcroy, C. Peter

    1988-01-01

    Physical and biological oceanography of the northern Bering Sea including the influence of the Yukon River were studied. Satellite data acquired by the Advanced Very High Resolution Radiometer (AVHRR), the LANDSAT Multispectral Scanner (MSS) and the Thematic Mapper (TM) sensor were used to detect sea surface temperatures and suspended sediments. Shipboard measurements of temperature, salinity and nutrients were acquired through the Inner Shelf Transfer and Recycling (ISHTAR) project and were compared to digitally enhanced and historical satellite images. The satellite data reveal north-flowing, warm water along the Alaskan coast that is highly turbid with complex patterns of surface circulation near the Yukon River delta. To the west near the Soviet Union, cold water, derived from an upwelling, mixes with shelf water and also flows north. The cold and warm water coincide with the Anadyr, Bering Shelf and Alaskan coastal water masses. Generally, warm Alaskan coastal water forms near the coast and extends offshore as the summer progresses. Turbid water discharged by the Yukon River progresses in the same fashion but extends northward across the entrance to Norton Sound, attaining its maximum surface extent in October. The Anadyr water flows northward and around St. Lawrence Island, but its extent is highly variable and depends upon mesoscale pressure fields in the Arctic Ocean and the Bering Sea.

  4. Hydrologic data from Nation, Kandik, and Yukon rivers, Yukon-Charley Rivers National Preserve, Alaska

    USGS Publications Warehouse

    Brabets, Timothy P.

    2001-01-01

    Flow data were collected from two adjacent rivers in Yukon?Charley Rivers National Preserve, Alaska?the Nation River (during 1991?2000) and the Kandik River (1994?2000)?and from the Yukon River (1950?2000) at Eagle, Alaska, upstream from the boundary of the preserve. These flow records indicate that most of the runoff from these rivers occurs from May through September and that the average monthly discharge during this period ranges from 1,172 to 2,210 cubic feet per second for the Nation River, from 1,203 to 2,633 cubic feet per second for the Kandik River, and from 112,000 to 224,000 cubic feet per second for the Yukon River. Water-quality data were collected for the Nation River and several of its tributaries from 1991 to 1992 and for the Yukon River at Eagle from 1950 to 1994. Three tributaries to the Nation River (Waterfall Creek, Cathedral Creek, and Hard Luck Creek) have relatively high concentrations of calcium, magnesium, and sulfate. These three watersheds are underlain predominantly by Paleozoic and Precambrian rocks. The Yukon River transports 33,000,000 tons of suspended sediment past Eagle each year. Reflecting the inputs from its major tributaries, the water of the Yukon River at Eagle is dominated by calcium?magnesium bicarbonate.

  5. Understanding the Complexities of Communicating Management Decisions on the Subsistence Use of Yukon River Salmon

    NASA Astrophysics Data System (ADS)

    Brooks, J. F.; Trainor, S.

    2017-12-01

    Over 20,000 residents in Alaska and Yukon Territory rely upon the Yukon River to provide them harvests of Pacific salmon each year. Salmon are a highly valued food resource and the practice of salmon fishing along the Yukon is deep rooted in local cultures and traditions. Potential future impacts of climate change on the health of Yukon River salmon stocks could be significant. Collaborative managerial processes which incorporate the viewpoints of subsistence stakeholders will be crucial in enabling communities and managerial institutions to adapt and manage these impacts. However, the massive extent of the Yukon River makes it difficult for communities rich with highly localized knowledge to situate themselves within a drainage-wide context of resource availability, and to fully understand the implications that management decisions may have for their harvest. Differences in salmon availability and abundance between the upper and lower Yukon, commercial vs. subsistence fishery interests, and enforcement of the international Pacific Salmon Treaty further complicate understanding and makes the topic of salmon as a subsistence resource a highly contentious issue. A map which synthesizes the presence and absence of Pacific salmon throughout the entire Yukon River drainage was requested by both subsistence fishers and natural resource managers in Alaska in order to help facilitate productive conversations about salmon management decisions. Interviews with Alaskan stakeholders with managerial, biological, and subsistence harvest backgrounds were carried out and a literature review was conducted in order to understand what such a map should and could accomplish. During the research process, numerous data gaps concerning the distribution of salmon along the Yukon River were discovered, and insights about the complexities involved in translating science when it is situated within a charged political, economic, and cultural context were revealed. Preliminary maps depicting

  6. MODIS-informed greenness responsesto daytime land surface temperaturefluctuations and wildfire disturbancesin the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Tan, Zhengxi; Liu, Shu-Guang; Jenkerson, Calli B.; Oeding, Jennifer; Wylie, Bruce K.; Rover, Jennifer R.; Young, Claudia J.

    2012-01-01

    Pronounced climate warming and increased wildfire disturbances are known to modify forest composition and control the evolution of the boreal ecosystem over the Yukon River Basin (YRB) in interior Alaska. In this study, we evaluate the post-fire green-up rate using the normalized difference vegetation index (NDVI) derived from 250 m 7 day eMODIS (an alternative and application-ready type of Moderate Resolution Imaging Spectroradiometer (MODIS) data) acquired between 2000 and 2009. Our analyses indicate measureable effects on NDVI values from vegetation type, burn severity, post-fire time, and climatic variables. The NDVI observations from both fire scars and unburned areas across the Alaskan YRB showed a tendency of an earlier start to the growing season (GS); the annual variations in NDVI were significantly correlated to daytime land surface temperature (LST) fluctuations; and the rate of post-fire green-up depended mainly on burn severity and the time of post-fire succession. The higher average NDVI values for the study period in the fire scars than in the unburned areas between 1950 and 2000 suggest that wildfires enhance post-fire greenness due to an increase in post-fire evergreen and deciduous species components

  7. An estimate of carbon emissions from 2004 wildfires across Alaskan Yukon River Basin

    USGS Publications Warehouse

    Tan, Zhengxi; Tieszen, Larry L.; Zhu, Zhiliang; Liu, Shuguang; Howard, Stephen M.

    2007-01-01

    BackgroundWildfires are an increasingly important component of the forces that drive the global carbon (C) cycle and climate change as progressive warming is expected in boreal areas. This study estimated C emissions from the wildfires across the Alaskan Yukon River Basin in 2004. We spatially related the firescars to land cover types and defined the C fractions of aboveground biomass and the ground layer (referring to the top 15 cm organic soil layer only in this paper) consumed in association with land cover types, soil drainage classes, and the C stocks in the ground layer.ResultsThe fires led to a burned area of 26,500 km2 and resulted in the total C emission of 81.1 ± 13.6 Tg (Tg, Teragram; 1 Tg = 1012 g) or 3.1 ± 0.7 kg C m-2 burned. Of the total C emission, about 73% and 27% could be attributed to the consumption of the ground layer and aboveground biomass, respectively.ConclusionThe predominant contribution of the ground layer to the total C emission implies the importance of ground fuel management to the control of wildfires and mitigation of C emissions. The magnitude of the total C emission depends on fire extent, while the C loss in kg C m-2 burned is affected strongly by the ground layer and soil drainage condition. The significant reduction in the ground layer by large fires may result in profound impacts on boreal ecosystem services with an increase in feedbacks between wildfires and climate change.

  8. Wearing surface testing : Yukon River bridge.

    DOT National Transportation Integrated Search

    2012-12-01

    The Yukon River Bridge, also known as the E.L. Patton Bridge, carries the twolane Dalton Highway and the trans-Alaska oil pipeline across the Yukon River at a 6% : grade. It is 30 feet wide, with 6 spans; it was designed to withstand -60 degrees Fahr...

  9. Low productivity of Chinook salmon strongly correlates with high summer stream discharge in two Alaskan rivers in the Yukon drainage

    USGS Publications Warehouse

    Neuswanger, Jason R.; Wipfli, Mark S.; Evenson, Matthew J.; Hughes, Nicholas F.; Rosenberger, Amanda E.

    2015-01-01

    Yukon River Chinook salmon (Oncorhynchus tshawytscha) populations are declining for unknown reasons, creating hardship for thousands of stakeholders in subsistence and commercial fisheries. An informed response to this crisis requires understanding the major sources of variation in Chinook salmon productivity. However, simple stock–recruitment models leave much of the variation in this system’s productivity unexplained. We tested adding environmental predictors to stock–recruitment models for two Yukon drainage spawning streams in interior Alaska — the Chena and Salcha rivers. Low productivity was strongly associated with high stream discharge during the summer of freshwater residency for young-of-the-year Chinook salmon. This association was more consistent with the hypothesis that sustained high discharge negatively affects foraging conditions than with acute mortality during floods. Productivity may have also been reduced in years when incubating eggs experienced major floods or cold summers and falls. These freshwater effects — especially density dependence and high discharge — helped explain population declines in both rivers. They are plausible as contributors to the decline of Chinook salmon throughout the Yukon River drainage.

  10. Environmental and hydrologic overview of the Yukon River basin, Alaska and Canada

    USGS Publications Warehouse

    Brabets, Timothy P.; Wang, Bronwen; Meade, Robert H.

    2000-01-01

    The Yukon River, located in northwestern Canada and central Alaska, drains an area of more than 330,000 square miles, making it the fourth largest drainage basin in North America. Approximately 126,000 people live in this basin and 10 percent of these people maintain a subsistence lifestyle, depending on the basin's fish and game resources. Twenty ecoregions compose the Yukon River Basin, which indicates the large diversity of natural features of the watershed, such as climate, soils, permafrost, and geology. Although the annual mean discharge of the Yukon River near its mouth is more than 200,000 cubic feet per second, most of the flow occurs in the summer months from snowmelt, rainfall, and glacial melt. Eight major rivers flow into the Yukon River. Two of these rivers, the Tanana River and the White River, are glacier-fed rivers and together account for 29 percent of the total water flow of the Yukon. Two others, the Porcupine River and the Koyukuk River, are underlain by continuous permafrost and drain larger areas than the Tanana and the White, but together contribute only 22 percent of the total water flow in the Yukon. At its mouth, the Yukon River transports about 60 million tons of suspended sediment annually into the Bering Sea. However, an estimated 20 million tons annually is deposited on flood plains and in braided reaches of the river. The waters of the main stem of the Yukon River and its tributaries are predominantly calcium magnesium bicarbonate waters with specific conductances generally less than 400 microsiemens per centimeter. Water quality of the Yukon River Basin varies temporally between summer and winter. Water quality also varies spatially among ecoregions

  11. Ichthyophoniasis: An emerging disease of Chinook salmon in the Yukon River

    USGS Publications Warehouse

    Kocan, R.; Hershberger, P.; Winton, J.

    2004-01-01

    Before 1985, Ichthyophonus was unreported among Pacific salmon Oncorhynchus spp. from the Yukon River; now it infects more than 40% of returning adult Chinook salmon O. tshawytscha. Overall infection prevalence reached about 45% in the Yukon River and about 30% in the Tanana River between 1999 and 2003. Mean infection prevalence was greater in females than males in the main-stem Yukon River during each of the 5 years of the study, but the infection prevalence in males increased each year until the difference was no longer significant. Clinical signs of ichthyophoniasis (presence of visible punctate white lesions in internal organs) were least at the mouth of the Yukon River (∼10%) but increased to 29% when fish reached the middle Yukon River and was 22% at the upper Tanana River. However, clinical signs increased each year from 7% in 1999 to 27% in 2003 at the mouth of the river. As fish approached the upper reaches of the Yukon River (Canada) and the spawning areas of the Chena and Salcha rivers (Alaska), infection prevalence dropped significantly to less than 15% in females on the Yukon River and less than 10% for both sexes in the Chena and Salcha rivers, presumably because of mortality among infected prespawn fish. Age was not a factor in infection prevalence, nor was the position of fish within the run. The source of infection was not determined, but Ichthyophonus was not found in 400 Pacific herring Clupea pallasi from the Bering Sea or in 120 outmigrating juvenile Chinook salmon from two drainages in Alaska and Canada. Freshwater burbot Lota lota from the middle Yukon River were subclinically infected with Ichthyophonus, but the origin and relationship of this agent to the Chinook salmon isolate is unknown.

  12. Accumulated state of the Yukon River watershed: part I critical review of literature.

    PubMed

    Dubé, Monique G; Muldoon, Breda; Wilson, Julie; Maracle, Karonhiakta'tie Bryan

    2013-07-01

    A consistent methodology for assessing the accumulating effects of natural and manmade change on riverine systems has not been developed for a whole host of reasons including a lack of data, disagreement over core elements to consider, and complexity. Accumulated state assessments of aquatic systems is an integral component of watershed cumulative effects assessment. The Yukon River is the largest free flowing river in the world and is the fourth largest drainage basin in North America, draining 855,000 km(2) in Canada and the United States. Because of its remote location, it is considered pristine but little is known about its cumulative state. This review identified 7 "hot spot" areas in the Yukon River Basin including Lake Laberge, Yukon River at Dawson City, the Charley and Yukon River confluence, Porcupine and Yukon River confluence, Yukon River at the Dalton Highway Bridge, Tolovana River near Tolovana, and Tanana River at Fairbanks. Climate change, natural stressors, and anthropogenic stresses have resulted in accumulating changes including measurable levels of contaminants in surface waters and fish tissues, fish and human disease, changes in surface hydrology, as well as shifts in biogeochemical loads. This article is the first integrated accumulated state assessment for the Yukon River basin based on a literature review. It is the first part of a 2-part series. The second article (Dubé et al. 2013a, this issue) is a quantitative accumulated state assessment of the Yukon River Basin where hot spots and hot moments are assessed outside of a "normal" range of variability. Copyright © 2012 SETAC.

  13. Alaska and Yukon Fires

    Atmospheric Science Data Center

    2014-05-15

    article title:  Smoke Signals from the Alaska and Yukon Fires   ... the Yukon Territory from mid-June to mid-July, 2004. Thick smoke particles filled the air during these fires, prompting Alaskan officials to issue air quality warnings. Some of the smoke from these fires was detected as far away as New Hampshire. These ...

  14. Export of Nitrogen From the Yukon River Basin to the Bering Sea

    NASA Astrophysics Data System (ADS)

    Dornblaser, M. M.; Striegl, R. G.

    2005-12-01

    The US Geological Survey measured nitrogen export from the 831,400 km2 Yukon River basin during 2001-04 as part of a five year water quality study of the Yukon River and its major tributaries. Concentrations of NO2+NO3, NH4+DON, and particulate N were measured ~6 times annually during open water and once under ice cover at three locations on the Yukon River, and on the Porcupine and Tanana Rivers. Concentration and continuous flow data were used to generate daily and annual loads of N species. NH4 concentration was generally negligible when compared to DON concentration, allowing for comparison of the relative importance of DIN vs. DON export at various watershed scales. NO2 concentration was also small compared to NO3. At Pilot Station, the last site on the Yukon before it flows into the Yukon Delta and the Bering Sea, DIN, DON, and particulate N loads averaged 19.3 × 106 kg/yr, 52.6 × 106 kg/yr, and 39.1 × 106 kg/yr, respectively. Normalized for the watershed area at Pilot Station, corresponding N yields were 1.65, 4.52, and 3.35 mmol/m2/yr. DIN yield for the Yukon at Pilot Station is substantially less than the NO3 flux reported for tropical/temperate rivers such as the Amazon, the Yangtze, and the Mississippi. DIN yield in the upper Yukon River basin is similar to that of the Mackenzie and other arctic rivers, but increases substantially downstream. This is likely due to development around Fairbanks in the Tanana River basin. When compared to other headwater basins in the upper Yukon, the Tanana basin yields about four times more DIN and two times more particulate N, while DON yields are only slightly elevated.

  15. Active Layer and Water Geochemistry Dynamics throughout the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Mutter, E. A.; Toohey, R.; Herman-Mercer, N. M.; Schuster, P. F.

    2017-12-01

    The hydrology of the Yukon River Basin has changed over the last several decades as evidenced by a variety of discharge, gravimetric, and geochemical analyses. The Indigenous Observation Network (ION), a community-based project, was initiated by the Yukon River Inter-Tribal Watershed Council and USGS. Capitalizing on existing USGS monitoring and research infrastructure and supplementing USGS collected data, ION investigates changes in surface water geochemistry and active layer dynamics throughout the Yukon River Basin. Over 1600 samples of surface water geochemistry (i.e., major ions, dissolved organic carbon, and 18O and 2H) have been collected at 35 sites throughout the Yukon River and its major tributaries over the past 15 years. Active layer dynamics (maximum thaw depth, soil temperature and moisture) have been collected at 20 sites throughout the Yukon River Basin for the past eight years. Important regional differences in geochemistry and active layer parameters linked to permafrost continuity and tributaries will be highlighted. Additionally, annual trends and seasonal dynamics describing the spatial and temporal heterogeneity of the watershed will be presented in the context of observed hydrological changes. These data assist the global effort to characterize arctic river fluxes and their relationship to the carbon cycle, weathering and permafrost degradation.

  16. Water quality in the Yukon River Basin, Alaska, water years 2006-2008

    USGS Publications Warehouse

    Schuster, Paul F.; Maracle, Karonhiakta'tie Bryan; Herman-Mercer, Nicole

    2010-01-01

    The Yukon River Inter-Tribal Watershed Council and the U.S. Geological Survey developed a water-quality monitoring program to address a shared interest in the water quality of the Yukon River and its relation to climate. This report contains water-quality data from samples collected in the Yukon River Basin during water years 2006 through 2008. A broad range of chemical analyses from 44 stations throughout the YRB are presented. On August 8, 2009 the USGS signed a Memorandum of Understanding with the Yukon River Inter-Tribal Watershed Council representing the culmination of 5 years of dedicated efforts to forge a working collaboration and partnership with expectations of continuing into the foreseeable future. The Memorandum of Understanding may be viewed at http://www.usgs.gov/mou/docs/yritwc_mou.pdf.

  17. Pleistocene vertebrates of the Yukon Territory

    NASA Astrophysics Data System (ADS)

    Harington, C. R.

    2011-08-01

    Unglaciated parts of the Yukon constitute one of the most important areas in North America for yielding Pleistocene vertebrate fossils. Nearly 30 vertebrate faunal localities are reviewed spanning a period of about 1.6 Ma (million years ago) to the close of the Pleistocene some 10 000 BP (radiocarbon years before present, taken as 1950). The vertebrate fossils represent at least 8 species of fishes, 1 amphibian, 41 species of birds and 83 species of mammals. Dominant among the large mammals are: steppe bison ( Bison priscus), horse ( Equus sp.), woolly mammoth ( Mammuthus primigenius), and caribou ( Rangifer tarandus) - signature species of the Mammoth Steppe fauna ( Fig. 1), which was widespread from the British Isles, through northern Europe, and Siberia to Alaska, Yukon and adjacent Northwest Territories. The Yukon faunas extend from Herschel Island in the north to Revenue Creek in the south and from the Alaskan border in the west to Ketza River in the east. The Yukon holds evidence of the earliest-known people in North America. Artifacts made from bison, mammoth and caribou bones from Bluefish Caves, Old Crow Basin and Dawson City areas show that people had a substantial knowledge of making and using bone tools at least by 25 000 BP, and possibly as early as 40 000 BP. A suggested chronological sequence of Yukon Pleistocene vertebrates ( Table 1) facilitates comparison of selected faunas and indicates the known duration of various taxa.

  18. Multidecadal increases in the Yukon River Basin of chemical fluxes as indicators of changing flowpaths, groundwater, and permafrost

    USGS Publications Warehouse

    Toohey, Ryan C; Herman-Mercer, Nicole M.; Schuster, Paul F.; Mutter, Edda A.; Koch, Joshua C.

    2016-01-01

    The Yukon River Basin, underlain by discontinuous permafrost, has experienced a warming climate over the last century that has altered air temperature, precipitation, and permafrost. We investigated a water chemistry database from 1982 to 2014 for the Yukon River and its major tributary, the Tanana River. Significant increases of Ca, Mg, and Na annual flux were found in both rivers. Additionally, SO4 and P annual flux increased in the Yukon River. No annual trends were observed for dissolved organic carbon (DOC) from 2001 to 2014. In the Yukon River, Mg and SO4 flux increased throughout the year, while some of the most positive trends for Ca, Mg, Na, SO4, and P flux occurred during the fall and winter months. Both rivers exhibited positive monthly DOC flux trends for summer (Yukon River) and winter (Tanana River). These trends suggest increased active layer expansion, weathering, and sulfide oxidation due to permafrost degradation throughout the Yukon River Basin.

  19. Influence of the Yukon River on the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, K.; Mcroy, C. P.

    1986-01-01

    The purpose is to use satellite data to study relationships between discharge of the Yukon River to currents and biologic productivity in the northern Bering Sea. Amended specific objectives are: to develop thermal, sediment and chlorophyll surface maps using thematic mapping (TM) data of the discharge of the Yukon River and the Alaska Coastal Current during the ice free season; to develop a historical model of the distribution of the Yukon River discharge and the Alaska Coastal Current using LANDSAT multispectral scanner (MMS) and NOAA satellite imagery; and to use high resolution TM data to define the surface dynamics of the front between the Alaska Coastal Current and the Bering Shelf/Anadyr Current. LANDSAT MSS and TM, and Advanced Very High Resolution Radiometer (AVHRR) data were recorded during the 1985 ice-free period. The satellite data coincided with shipboard measurements acquired by Inner Self Transfer and Recycling scientists. Circumstances were such, that on July 5 and July 22, all three sensors recorded data that has been registered to a common map projection and map base, then contrast stretched, color composited, and density sliced.

  20. Annual estimates of water and solute export from 42 tributaries to the Yukon River

    USGS Publications Warehouse

    Frederick Zanden,; Suzanne P. Anderson,; Striegl, Robert G.

    2012-01-01

    Annual export of 11 major and trace solutes for the Yukon River is found to be accurately determined based on summing 42 tributary contributions. These findings provide the first published estimates of tributary specific distribution of solutes within the Yukon River basin. First, we show that annual discharge of the Yukon River can be computed by summing calculated annual discharges from 42 tributaries. Annual discharge for the tributaries is calculated from the basin area and average annual precipitation over that area using a previously published regional regression equation. Based on tributary inputs, we estimate an average annual discharge for the Yukon River of 210 km3 year–1. This value is within 1% of the average measured annual discharge at the U.S. Geological Survey gaging station near the river terminus at Pilot Station, AK, for water years 2001 through 2005. Next, annual loads for 11 solutes are determined by combining annual discharge with point measurements of solute concentrations in tributary river water. Based on the sum of solutes in tributary water, we find that the Yukon River discharges approximately 33 million metric tons of dissolved solids each year at Pilot Station. Discharged solutes are dominated by cations calcium and magnesium (5.65 × 109 and 1.42 × 109 g year–1) and anions bicarbonate and sulphate (17.3 × 109 and 5.40 × 109 g year–1). These loads compare well with loads calculated independently at the three continuous gaging stations along the Yukon River. These findings show how annual solute yields vary throughout a major subarctic river basin and that accurate estimates of total river export can be determined from calculated tributary contributions.

  1. Characteristics of sediment discharge in the subarctic Yukon River, Alaska

    USGS Publications Warehouse

    Chikita, K.A.; Kemnitz, R.; Kumai, R.

    2002-01-01

    The characteristics of sediment discharge in the Yukon River, Alaska were investigated by monitoring water discharge, water turbidity and water temperature. The river-transported sediment, 90 wt.% or more, consists of silt and clay (grain size ??? 62.5 ??m), which probably originated in the glacier-covered mountains mostly in the Alaska Range. For early June to late August 1999, we continuously measured water turbidity and temperature near the estuary and in the middle of Yukon River by using self-recording turbidimeters and temperature data loggers. The water turbidity (ppm) was converted to suspended sediment concentration (SSC; mg/l) of river water, using a relation between simultaneous turbidity and SSC at each of the two sites, and then, the suspended sediment discharge, approximately equal to water discharge times SSC, was numerically obtained every 1 or 2 h. It should be noted that the sediment discharge in the Yukon River is controlled by SSC rather than water discharge. As a result, a peak sediment discharge occurred in mid or late August by local sediment runoffs due to glacier-melt (or glacier-melt plus rainfall), while a peak water discharge was produced by snowmelt in late June or early July. Application of the "extended Shields diagram" indicates that almost all the river-transported sediments are under complete suspension. ?? 2002 Elsevier Science B.V. All rights reserved.

  2. Three Rivers: Protecting the Yukon's Great Boreal Wilderness

    Treesearch

    Juri Peepre

    2007-01-01

    The Three Rivers Project in the Yukon, Canada, aims to protect a magnificent but little known 30,000 km2 (11,583 miles2) wilderness in the Peel watershed, using the tools of science, visual art, literature, and community engagement. After completing ecological inventories, conservation values maps, and community trips on the Wind, Snake, and Bonnet Plume rivers, the...

  3. Water and Sediment Quality in the Yukon River Basin, Alaska, During Water Year 2001

    USGS Publications Warehouse

    Schuster, Paul F.

    2003-01-01

    Overview -- This report contains water-quality and sediment-quality data from samples collected in the Yukon River Basin during water year 2001 (October 2000 through September 2001). A broad range of chemical and biological analyses from three sets of samples are presented. First, samples were collected throughout the year at five stations in the basin (three on the mainstem Yukon River, one each on the Tanana and Porcupine Rivers). Second, fecal indicators were measured on samples from drinking-water supplies collected near four villages. Third, sediment cores from five lakes throughout the Yukon Basin were sampled to reconstruct historic trends in the atmospheric deposition of trace elements and hydrophobic organic compounds.

  4. Differences in Ichthyophonus prevalence and infection severity between upper Yukon River and Tanana River chinook salmon, Oncorhynchus tshawytscha (Walbaum), stocks

    USGS Publications Warehouse

    Kocan, R.; Hershberger, P.

    2006-01-01

    Two genetically distinct populations of chinook salmon, Oncorhynchus tshawytscha (Walbaum), were simultaneously sampled at the confluence of the Yukon and Tanana rivers in 2003. Upper Yukon-Canadian fish had significantly higher infection prevalence as well as more severe infections (higher parasite density in heart tissue) than the lower Yukon-Tanana River fish. Both populations had migrated the same distance from the mouth of the Yukon River at the time of sampling but had significantly different distances remaining to swim before reaching their respective spawning grounds. Multiple working hypotheses are proposed to explain the differences between the two stocks: (1) the two genetically distinct populations have different inherent resistance to infection, (2) genetically influenced differences in feeding behaviour resulted in temporal and/or spatial differences in exposure, (3) physiological differences resulting from different degrees of sexual maturity influenced the course of disease, and (4) the most severely infected Tanana River fish either died en route or fatigued and were unable to complete their migration to the Tanana River, thus leaving a population of apparently healthier fish. ?? 2006 Blackwell Publishing Ltd.

  5. Studies of Climate Change in the Yukon River Basin: Connecting Community and Science Through a Unique Partnership

    USGS Publications Warehouse

    Schuster, Paul F.; Maracle, Karonhiakta'tie Byran

    2010-01-01

    An exciting new partnership between the U.S. Geological Survey (USGS) and the Yukon River Inter-Tribal Watershed Council (YRITWC) is yielding critical data for the assessment of climate change effects in the Yukon River Basin. The foundation of this partnership is a shared interest in the current and future water quality of the Yukon River and its relation to climate. The USGS began a landmark study of the Yukon River and its major tributaries in 2000. A key objective of this study is to establish a baseline dataset of water quality, which will serve as an important frame of reference to assess future changes in the basin that may result from a warmer climate.

  6. Mercury interferes with endogenous antioxidant levels in Yukon River subsistence-fed sled dogs

    NASA Astrophysics Data System (ADS)

    Dunlap, Kriya L.; Reynolds, Arleigh J.; Gerlach, S. Craig; Duffy, Lawrence K.

    2011-10-01

    Before adopting modern corn-and-grain-based western processed diets, circumpolar people had a high fat and protein subsistence diet and exhibited a low incidence of obesity, diabetes and cardiovascular disease. Some health benefits are attributable to a subsistence diet that is rich in omega-3 fatty acids and antioxidants. Pollution, both global and local, is a threat to wild foods, as it introduces contaminants into the food system. Northern indigenous people and their sled dogs are exposed to a variety of contaminants, including mercury, that accumulate in the fish and game that they consume. The sled dogs in Alaskan villages are maintained on the same subsistence foods as their human counterparts, primarily salmon, and therefore they can be used as a food systems model for researching the impact of changes in dietary components. In this study, the antioxidant status and mercury levels were measured for village sled dogs along the Yukon River. A reference kennel, maintained on a nutritionally balanced commercial diet, was also measured for comparison. Total antioxidant status was inversely correlated with the external stressor mercury.

  7. Water and sediment quality of the Yukon River and its tributaries, from Eagle to St. Marys, Alaska, 2002-2003

    USGS Publications Warehouse

    Dornblaser, Mark M.; Halm, Douglas R.

    2006-01-01

    The Yukon River basin is a vast and diverse ecosystem covering more than 330,000 square miles, an area larger than Texas. Approximately 126,000 people live within the basin and depend on the Yukon River and its tributaries for drinking water, commerce, and recreational and subsistence fish and game resources. Much of the Yukon River basin is underlain by permafrost containing vast amounts of organic carbon and nutrients. Recent climatic warming of the basin has resulted in lengthening of the growing season, melting of permafrost, deepening of the soil active layer, drying of upland soils, and shrinking of wetlands. These mostly terrestrial effects also affect the hydrology of the basin, changing the timing, magnitude, and fate of water and dissolved and particulate materials delivery to the Yukon River and its tributaries. As permafrost melts, stored carbon and nutrients are expected to become available for decomposition by soil organisms or for export downstream and to the Bering Sea. Such changes can have numerous, far-reaching effects on the ecosystem, including increased emission of greenhouse gases such as carbon dioxide and methane; changes in stream productivity, including salmon populations; changes in the productivity and chemistry of the Bering Sea; and increased fire frequency. One important question is whether organic carbon export to rivers will increase or decrease downstream from large wetland areas presently having substantial carbon storage, such as Yukon Flats. Because very few historical water-quality data are available for the Yukon River basin, scientists are unable to quantitatively assess potential effects of climate warming on aquatic ecosystems in the basin. In order to address these concerns, the U.S. Geological Survey conducted a comprehensive baseline water-quality characterization of the Yukon River and its major tributaries during 2000-05. The study included frequent water-quality sampling at a fixed-site network. In addition to the

  8. Environmental Assessment for the Expansion of the Yukon Measurement and Debriefing System in the Fox and Yukon MOAs

    DTIC Science & Technology

    2006-05-01

    River, Porcupine River, Chandalar River, and the upper portion of the Yukon River. The southern portion of the area is drained by the Fortymile River...physiographic features in the central 17 EA for Expansion of YMDS April2006 portion are the Porcupine Plateau and the Yukon Flats. The Yukon Flats...mile. The Fortymile caribou herd utilizes the surrounding area as its principle winter range. Since 1995, the Fortymile caribou herd has increased

  9. Influence of the Yukon River on the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, K.; Mcroy, C. P.

    1987-01-01

    The distribution of near-surface, turbid water, discharged by the Yukon River, was studied based on analysis of satellite imagery. The interannual analyses indicates that the net flow of near-surface, turbid water is northward of the delta across the entrance to Norton Sound. Only turbid water to the east enters Norton Sound and consists of 25% of the total area. Approximately 10% of the water circulates into the sound along the southern coast and is lost to view in the vicinity of Unalakleet. Suspended sediments transported by this southern circulation are primarily deposited along the southern coast. Three distinct zones within the turbid water were identified based on relative brightness levels. These zones appear to be primarily related to differences in suspended-sediment concentrations and position of the sediments in the water column. The extent of turbid water varies seasonally. It is most extensive June through October even though discharge of the Yukon River decreases substantially after July.

  10. Transport of Water, Carbon, and Sediment Through the Yukon River Basin

    USGS Publications Warehouse

    Brabets, Timothy P.; Schuster, Paul F.

    2008-01-01

    INTRODUCTION In 2001, the U.S. Geological Survey (USGS) began a water-quality study of the Yukon River. The Yukon River Basin (YRB), which encompasses 330,000 square miles in northwestern Canada and central Alaska (fig. 1), is one of the largest and most diverse ecosystems in North America. The Yukon River is more than 1,800 miles long and is one of the last great uncontrolled rivers in the world, and is essential to the eastern Bering Sea and Chukchi Sea ecosystems, providing freshwater runoff, sediments, and nutrients (Brabets and others, 2000). Despite its remoteness, recent studies (Hinzman and others, 2005; Walvoord and Striegl, 2007) indicate the YRB is changing. These changes likely are in response to a warming trend in air temperature of 1.7i??C from 1951 to 2001 (Hartmann and Wendler, 2005). As a result of this warming trend, permafrost is thawing in the YRB, ice breakup occurs earlier on the main stem of the Yukon River and its tributaries, and timing of streamflow and movement of carbon and sediment through the basin is changing (Hinzman and others, 2005; Walvoord and Striegl, 2007). One of the most striking characteristics in the YRB is its seasonality. In the YRB, more than 75 percent of the annual streamflow runoff occurs during a five month period, May through September. This is important because streamflow determines when, where, and how much of a particular constituent will be transported. As an example, more than 95 percent of all sediment transported during an average year also occurs during this period (Brabets and others, 2000). During the other 7 months, streamflow, concentrations of sediment and other water-quality constituents are low and little or no sediment transport occurs in the Yukon River and its tributaries. Streamflow and water-quality data have been collected at more than 50 sites in the YRB (Dornblaser and Halm, 2006; Halm and Dornblaser, 2007). Five sites have been sampled more than 30 times and others have been sampled twice

  11. Influences of glacial melt and permafrost thaw on the age of dissolved organic carbon in the Yukon River basin

    USGS Publications Warehouse

    Aiken, George R.; Spencer, Robert G.M.; Striegl, Robert G.; Schuster, Paul F.; Raymond, Peter A.

    2014-01-01

    Responses of near-surface permafrost and glacial ice to climate change are of particular significance for understanding long-term effects on global carbon cycling and carbon export by high-latitude northern rivers. Here we report Δ14C-dissolved organic carbon (DOC) values and dissolved organic matter optical data for the Yukon River, 15 tributaries of the Yukon River, glacial meltwater, and groundwater and soil water end-member sources draining to the Yukon River, with the goal of assessing mobilization of aged DOC within the watershed. Ancient DOC was associated with glacial meltwater and groundwater sources. In contrast, DOC from watersheds dominated by peat soils and underlain by permafrost was typically enriched in Δ14C indicating that degradation of ancient carbon stores is currently not occurring at large enough scales to quantitatively influence bulk DOC exports from those landscapes. On an annual basis, DOC exported was predominantly modern during the spring period throughout the Yukon River basin and became older through summer-fall and winter periods, suggesting that contributions of older DOC from soils, glacial meltwaters, and groundwater are significant during these months. Our data indicate that rapidly receding glaciers and increasing groundwater inputs will likely result in greater contributions of older DOC in the Yukon River and its tributaries in coming decades.

  12. Distribution and landscape controls of organic layer thickness and carbon within the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Pastick, Neal J.; Rigge, Matthew B.; Wylie, Bruce K.; Jorgenson, M. Torre; Rose, Joshua R.; Johnson, Kristofer D.; Ji, Lei

    2014-01-01

    Understanding of the organic layer thickness (OLT) and organic layer carbon (OLC) stocks in subarctic ecosystems is critical due to their importance in the global carbon cycle. Moreover, post-fire OLT provides an indicator of long-term successional trajectories and permafrost susceptibility to thaw. To these ends, we 1) mapped OLT and associated uncertainty at 30 m resolution in the Yukon River Basin (YRB), Alaska, employing decision tree models linking remotely sensed imagery with field and ancillary data, 2) converted OLT to OLC using a non-linear regression, 3) evaluate landscape controls on OLT and OLC, and 4) quantified the post-fire recovery of OLT and OLC. Areas of shallow (2 = 0.68; OLC: R2 = 0.66), where an average of 16 cm OLT and 5.3 kg/m2 OLC were consumed by fires. Strong predictors of OLT included climate, topography, near-surface permafrost distributions, soil wetness, and spectral information. Our modeling approach enabled us to produce regional maps of OLT and OLC, which will be useful in understanding risks and feedbacks associated with fires and climate feedbacks.

  13. Floodplain soil organic carbon storage in the central Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Lininger, K.; Wohl, E.

    2017-12-01

    As rivers transport sediment, organic matter, and large wood, they can deposit those materials in their floodplains, storing carbon. One aspect of the carbon cycle that isn't well understood is how much carbon is stored in rivers and floodplains. There may be more carbon in rivers and floodplains than previously thought. This is important for accounting for all aspects of the carbon cycle, which is the movement of carbon among the land, ocean, and atmosphere. We are quantifying that storage in high latitude floodplains through fieldwork along five rivers in the central Yukon River Basin within the Yukon Flats National Wildlife Refuge in interior Alaska. We find that the geomorphic environment and geomorphic characteristics of rivers influence the spatial distribution of carbon on the landscape, and that floodplains may be disproportionally important for carbon storage compared to other areas. Our study area contains discontinuous permafrost, which is soil that is perennially frozen, and is warming quickly due to climate change, as in other high latitude regions. The large amount of carbon stored in the subsurface and in permafrost in the high latitudes highlights the importance of understanding where carbon is stored within rivers and floodplains in these regions and how long that carbon remains in storage. Our research helps inform how river systems influence the carbon cycle in a region undergoing rapid change.

  14. Water and Sediment Quality in the Yukon River and its Tributaries Between Atlin, British Columbia, Canada, and Eagle, Alaska, USA, 2004

    USGS Publications Warehouse

    Halm, Douglas R.; Dornblaser, Mark M.

    2007-01-01

    The Yukon River basin is the fourth largest watershed in North America at 831,400 square kilometers (km2). Approximately 126,000 people live within the basin and depend on the Yukon River and its tributaries for drinking water, commerce, subsistence, and recreational fish and game resources. Climate warming in the Arctic and Subarctic regions encompassing the Yukon basin has recently become a concern because of possible far-reaching effects on the ecosystem. Large amounts of carbon and nutrients are stored in permafrost and have potential for release in response to this warming. These changes in carbon and nutrient cycling may result in changes in stream chemistry and productivity, including salmon populations, and ultimately changes in the chemistry and productivity of the Bearing Sea. To address these concerns, the U.S. Geological Survey (USGS) conducted a 5-year comprehensive water-quality study of the Yukon River and its major tributaries starting in 2000. The study included frequent water-quality sampling at a fixed site network as well as intensive sampling along the Yukon River and its major tributaries. This report contains observations of water and sediment quantity and quality of the Yukon River and its tributaries in Canada during 2004. Chemical, biological, physical, and discharge data are presented for the reach of river between Atlin, British Columbia, Canada, and Eagle, Alaska, USA.

  15. Juvenile Chinook Salmon abundance in the northern Bering Sea: Implications for future returns and fisheries in the Yukon River

    NASA Astrophysics Data System (ADS)

    Murphy, James M.; Howard, Kathrine G.; Gann, Jeanette C.; Cieciel, Kristin C.; Templin, William D.; Guthrie, Charles M.

    2017-01-01

    Juvenile Chinook Salmon (Oncorhynchus tshawytscha) abundance in the northern Bering Sea is used to provide insight into future returns and fisheries in the Yukon River. The status of Yukon River Chinook Salmon is of concern due to recent production declines and subsequent closures of commercial, sport, and personal use fisheries, and severe restrictions on subsistence fisheries in the Yukon River. Surface trawl catch data, mixed layer depth adjustments, and genetic stock mixtures are used to estimate juvenile abundance for the Canadian-origin stock group from the Yukon River. Abundance ranged from a low of 0.62 million in 2012 to a high of 2.58 million in 2013 with an overall average of 1.5 million from 2003 to 2015. Although abundance estimates indicate that average survival is relatively low (average of 5.2%), juvenile abundance was significantly correlated (r=0.87, p=0.005) with adult returns, indicating that much of the variability in survival occurs during early life-history stages (freshwater and initial marine). Juvenile abundance in the northern Bering Sea has increased since 2013 due to an increase in early life-history survival (average juveniles-per-spawner increased from 29 to 59). The increase in juvenile abundance is projected to produce larger runs and increased subsistence fishing opportunities for Chinook Salmon in the Yukon River as early as 2016.

  16. Trends in streamflow in the Yukon River Basin from 1944 to 2005 and the influence of the Pacific Decadal Oscillation

    USGS Publications Warehouse

    Brabets, T.P.; Walvoord, Michelle Ann

    2009-01-01

    Streamflow characteristics in the Yukon River Basin of Alaska and Canada have changed from 1944 to 2005, and some of the change can be attributed to the two most recent modes of the Pacific Decadal Oscillation (PDO). Seasonal, monthly, and annual stream discharge data from 21 stations in the Yukon River Basin were analyzed for trends over the entire period of record, generally spanning 4-6 decades, and examined for differences between the two most recent modes of the PDO: cold-PDO (1944-1975) and warm-PDO (1976-2005) subsets. Between 1944 and 2005, average winter and April flow increased at 15 sites. Observed winter flow increases during the cold-PDO phase were generally limited to sites in the Upper Yukon River Basin. Positive trends in winter flow during the warm-PDO phase broadened to include stations in the Middle and Lower Yukon River drainage basins. Increases in winter streamflow most likely result from groundwater input enhanced by permafrost thawing that promotes infiltration and deeper subsurface flow paths. Increased April flow may be attributed to a combination of greater baseflow (from groundwater increases), earlier spring snowmelt and runoff, and increased winter precipitation, depending on location. Calculated deviations from long-term mean monthly discharges indicate below-average flow in the winter months during the cold PDO and above-average flow in the winter months during the warm PDO. Although not as strong a signal, results also support the reverse response during the summer months: above-average flow during the cold PDO and below-average flow during the warm PDO. Changes in the summer flows are likely an indirect consequence of the PDO, resulting from earlier spring snowmelt runoff and also perhaps increased summer infiltration and storage in a deeper active layer. Annual discharge has remained relatively unchanged in the Yukon River Basin, but a few glacier-fed rivers demonstrate positive trends, which can be attributed to enhanced glacier

  17. Carbon dioxide and methane emissions from the Yukon River system

    USGS Publications Warehouse

    Striegl, Robert G.; Dornblaser, Mark M.; McDonald, Cory P.; Rover, Jennifer R.; Stets, Edward G.

    2012-01-01

    Carbon dioxide (CO2) and methane (CH4) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO2 and CH4 partial pressures (pCO2, pCH4) and flux across the water-air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO2emissions were 7.68 Tg C yr−1 (95% CI: 5.84 −10.46), averaging 750 g C m−2 yr−1 normalized to water surface area, and 9.0 g C m−2 yr−1 normalized to river basin area. River CH4 emissions totaled 55 Gg C yr−1 or 0.7% of the total mass of C emitted as CO2 plus CH4 and ∼6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO2 and CH4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.

  18. Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential future responses to climate change

    USGS Publications Warehouse

    Dornblaser, Mark M.; Striegl, Robert G.

    2009-01-01

    Loads and yields of suspended sediment and carbonate were measured and modeled at three locations on the Yukon, Tanana, and Porcupine Rivers in Alaska during water years 2001–2005 (1 October 2000 to 30 September 2005). Annual export of suspended sediment and carbonate upstream from the Yukon Delta averaged 68 Mt a−1 and 387 Gg a−1, respectively, with 50% of the suspended sediment load originating in the Tanana River Basin and 88% of the carbonate load originating in the White River Basin. About half the annual suspended sediment export occurred during spring, and half occurred during summer‐autumn, with very little export in winter. On average, a minimum of 11 Mt a−1 of suspended sediment is deposited in floodplains between Eagle, Alaska, and Pilot Station, Alaska, on an annual basis, mostly in the Yukon Flats. There is about a 27% loss in the carbonate load between Eagle and Yukon River near Stevens Village, with an additional loss of about 29% between Stevens Village and Pilot Station, owing to a combination of deposition and dissolution. Comparison of current and historical suspended sediment loads for Tanana River suggests a possible link between suspended sediment yield and the Pacific decadal oscillation.

  19. Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential future responses to climate change

    NASA Astrophysics Data System (ADS)

    Dornblaser, Mark M.; Striegl, Robert G.

    2009-06-01

    Loads and yields of suspended sediment and carbonate were measured and modeled at three locations on the Yukon, Tanana, and Porcupine Rivers in Alaska during water years 2001-2005 (1 October 2000 to 30 September 2005). Annual export of suspended sediment and carbonate upstream from the Yukon Delta averaged 68 Mt a-1 and 387 Gg a-1, respectively, with 50% of the suspended sediment load originating in the Tanana River Basin and 88% of the carbonate load originating in the White River Basin. About half the annual suspended sediment export occurred during spring, and half occurred during summer-autumn, with very little export in winter. On average, a minimum of 11 Mt a-1 of suspended sediment is deposited in floodplains between Eagle, Alaska, and Pilot Station, Alaska, on an annual basis, mostly in the Yukon Flats. There is about a 27% loss in the carbonate load between Eagle and Yukon River near Stevens Village, with an additional loss of about 29% between Stevens Village and Pilot Station, owing to a combination of deposition and dissolution. Comparison of current and historical suspended sediment loads for Tanana River suggests a possible link between suspended sediment yield and the Pacific decadal oscillation.

  20. Biodegradability of dissolved organic carbon in the Yukon River and its tributaries: Seasonality and importance of inorganic nitrogen

    USGS Publications Warehouse

    Wickland, Kimberly P.; Aiken, George R.; Butler, Kenna D.; Dornblaser, Mark M.; RGM Spencer,; Striegl, Robert G.

    2012-01-01

    Northern high-latitude rivers transport large amounts of terrestrially derived dissolved organic matter (DOM) from boreal and arctic ecosystems to coastal areas and oceans. Current knowledge of the biodegradability of DOM in these rivers is limited, particularly for large rivers discharging to the Arctic Ocean. We conducted a seasonally comprehensive study of biodegradable dissolved organic carbon (BDOC) dynamics in the Yukon River and two of its tributaries in Alaska, USA. Distinct seasonal patterns of BDOC, consistent across a wide range of watershed size, indicate BDOC is transported year-round. Relative biodegradability (%BDOC) was greatest during winter, and decreased into spring and summer. Due to large seasonal differences in DOC concentration, the greatest concentrations of BDOC (mg C L−1) occurred during spring freshet, followed by winter and summer. While chemical composition of DOM was an important driver of BDOC, the overriding control of BDOC was mineral nutrient availability due to wide shifts in carbon (C) and nitrogen (N) stoichiometry across seasons. We calculated seasonal and annual loads of BDOC exported by the Yukon River by applying measured BDOC concentrations to daily water discharge values, and also by applying an empirical correlation between %BDOC and the ratio of DOC to dissolved inorganic N (DIN) to total DOC loads. The Yukon River exports ∼0.2 Tg C yr−1 as BDOC that is decomposable within 28 days. This corresponds to 12–18% of the total annual DOC export. Furthermore, we calculate that the six largest arctic rivers, including the Yukon River, collectively export ∼2.3 Tg C yr−1 as BDOC to the Arctic Ocean.

  1. The plume of the Yukon River in relation to the oceanography of the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, Kenneson G.; Mcroy, C. Peter; Ahlnas, Kristina; Springer, Alan

    1989-01-01

    The ecosystem of the northern Bering-Sea shelf was studied using data from the NOAA Very High Resolution Radiometer and AVHRR and the Landsat MSS and Thematic Mapper (TM) in conjunction with shipboard measurements. Emphasis was placed on the influence of the Yukon River on this inner shelf environment and on the evaluation of the utility of the new Landsat TM data for oceanography. It was found that the patterns of water mass distribution obtained from satellite images agreed reasonably well with the areal patterns of temperature, salinity, and phytoplankton distributions. The AVHRR, MSS, and TM data show that the Yukon-River discharge is warmer and more turbid than the surrounding coastal water that originates to the south; thus, the Yukon water contributes to the higher temperatures and lower transmissivity of the coastal water. The high resolution of the TM thermal IR band made it possible to observe complex patterns and structures in the surface water that could not be resolved on previous data sets.

  2. Overview of environmental and hydrogeologic conditions at Fort Yukon, Alaska

    USGS Publications Warehouse

    Nakanishi, Allan S.; Dorava, Joseph M.

    1994-01-01

    The village of Fort Yukon along the Yukon River in east-central Alaska has long cold winters and short summers. The Federal Aviation Administration operates and supports some airport facilities in Fort Yukon and is evaluating the severity of environmental contamination and options for remediation of such contamination at their facilites. Fort Yukon is located on the flood plain of the Yukon River and obtains its drinking water from a shallow aquifer located in the thick alluvium underlying the village. Surface spills and disposal of hazardous materials combined with annual flooding of the Yukon River may affect the quality of the ground water. Alternative drinking-water sources are available from local surface-water bodies or from presently unidentified confined aquifers.

  3. Relationship between passive microwave-derived snowmelt and surface-measured discharge, Wheaton River, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Ramage, J. M.; McKenney, R. A.; Thorson, B.; Maltais, P.; Kopczynski, S. E.

    2006-03-01

    Snow volume and melt timing are major factors influencing the water cycle at northern high altitudes and latitudes, yet both are hard to quantify or monitor in remote mountainous regions. Twice-daily special sensor microwave imager (SSM/I) passive microwave observations of seasonal snow melt onset in the Wheaton River basin, Yukon Territory, Canada (60 ° 0805N, 134 ° 5345W), are used to test the idea that melt onset date and duration of snowpack melt-refreeze fluctuations control the timing of the early hydrograph peaks with predictable lags. This work uses the SSM/I satellite data from 1988 to 2002 to evaluate the chronology of melt and runoff patterns in the upper Yukon River basin. The Wheaton River is a small (875 km2) tributary to the Yukon, and is a subarctic, partly glacierized heterogeneous basin with near-continuous hydrographic records dating back to 1966. SSM/I pixels are sensitive to melt onset due to the strong increase in snow emissivity, and have a robust signal, in spite of coarse (>25 × 25 km2) pixel resolution and varied terrain. Results show that Wheaton River peak flows closely follow the end of large daily variations in brightness temperature of pixels covering the Wheaton River, but the magnitude of flow is highly variable, as might be expected from interannual snow mass variability. Spring rise in the hydrograph follows the end of high diurnal brightness temperature (Tb) amplitude variations (DAV) by 0 to 5 days approximately 90% of the time for this basin. Subsequent work will compare these findings for a larger (7250 km2), unglacierized tributary, the Ross River, which is farther northeast (61 ° 5940N, 132 ° 2240W) in the Yukon Territory. These techniques will also be used to try to determine the improvement in melt detection and runoff prediction from the higher resolution (15 × 15 km2) advanced microwave scanning radiometer for EOS (AMSR-E) sensor.

  4. Quantitative mineralogy of the Yukon River system: Changes with reach and season, and determining sediment provenance

    USGS Publications Warehouse

    Eberl, D.D.

    2004-01-01

    The mineralogy of Yukon River basin sediment has been studied by quantitative X-ray diffraction. Bed, beach, bar, and suspended sediments were analyzed using the RockJock computer program. The bed sediments were collected from the main stem and from selected tributaries during a single trip down river, from Whitehorse to the Yukon River delta, during the summer of 2001. Beach and bar sediments were collected from the confluence region of the Tanana and Yukon Rivers during the summer of 2003. Suspended sediments were collected at three stations on the Yukon River and from a single station on the Tanana River at various times during the summers of 2001 through 2003, with the most complete set of samples collected during the summer of 2002. Changes in mineralogy of Yukon River bed sediments are related to sediment dilution or concentration effects from tributary sediment and to chemical weathering during transport. Carbonate minerals compose about 2 wt% of the bed sediments near Whitehorse, but increase to 14 wt% with the entry of the White River tributary above Dawson. Thereafter, the proportion of carbonate minerals decreases downstream to values of about 1 to 7 wt% near the mouth of the Yukon River. Quartz and feldspar contents of bed sediments vary greatly with the introduction of Pelly River and White River sediments, but thereafter either increase irregularly (quartz from 20 to about 50 wt%) or remain relatively constant (feldspar at about 35 wt%) with distance downstream. Clay mineral content increases irregularly downstream from about 15 to about 30 wt%. The chief clay mineral is chlorite, followed by illite + smectite; there is little to no kaolinite. The total organic carbon content of the bed sediments remains relatively constant with distance for the main stem (generally 1 to 2 wt%, with one exception), but fluctuates for the tributaries (1 to 6 wt%). The mineralogies of the suspended sediments and sediment flow data were used to calculate the amount of

  5. Strategic needs of water on the Yukon: an interdisciplinary approach to studying hydrology and climate change in the Lower Yukon River Basin

    USGS Publications Warehouse

    Herman-Mercer, Nicole M.; Schuster, Paul F.

    2014-01-01

    Strategic Needs of Water on the Yukon (SNOWY) is an interdisciplinary research project funded by the National Science Foundation (NSF; http://www.nsf.gov/). The SNOWY team is made up of a diverse group of researchers from different backgrounds and organizations. This partnership between scientists from different disciplines (hydrology, geography, and social science), government agencies, nonprofit organizations, universities, and Lower Yukon River Basin (LYRB) and Yukon-Kuskokwim (YK) Delta communities provided an opportunity to study the effects of climate change using a holistic approach. The Arctic and Subarctic are experiencing environmental change at a rate faster than the rest of the world, and the lack of historical baseline data in these often remote locations makes understanding and predicting regional climate change difficult. This project focused on collecting data to fill in these gaps by using both quantitative and qualitative methodologies to tell the story of environmental change in this region as told by the physical data and the people who rely on this landscape.

  6. Using a genetic mixture model to study phenotypic traits: Differential fecundity among Yukon river Chinook Salmon

    USGS Publications Warehouse

    Bromaghin, Jeffrey F.; Evenson, D.F.; McLain, T.H.; Flannery, B.G.

    2011-01-01

    Fecundity is a vital population characteristic that is directly linked to the productivity of fish populations. Historic data from Yukon River (Alaska) Chinook salmon Oncorhynchus tshawytscha suggest that length‐adjusted fecundity differs among populations within the drainage and either is temporally variable or has declined. Yukon River Chinook salmon have been harvested in large‐mesh gill‐net fisheries for decades, and a decline in fecundity was considered a potential evolutionary response to size‐selective exploitation. The implications for fishery conservation and management led us to further investigate the fecundity of Yukon River Chinook salmon populations. Matched observations of fecundity, length, and genotype were collected from a sample of adult females captured from the multipopulation spawning migration near the mouth of the Yukon River in 2008. These data were modeled by using a new mixture model, which was developed by extending the conditional maximum likelihood mixture model that is commonly used to estimate the composition of multipopulation mixtures based on genetic data. The new model facilitates maximum likelihood estimation of stock‐specific fecundity parameters without first using individual assignment to a putative population of origin, thus avoiding potential biases caused by assignment error. The hypothesis that fecundity of Chinook salmon has declined was not supported; this result implies that fecundity exhibits high interannual variability. However, length‐adjusted fecundity estimates decreased as migratory distance increased, and fecundity was more strongly dependent on fish size for populations spawning in the middle and upper portions of the drainage. These findings provide insights into potential constraints on reproductive investment imposed by long migrations and warrant consideration in fisheries management and conservation. The new mixture model extends the utility of genetic markers to new applications and can be

  7. A promising tool for subsurface permafrost mapping-An application of airborne geophysics from the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Abraham, Jared E.

    2011-01-01

    In the area of Fort Yukon, the AEM survey shows elevated resistivities extending to depth, likely indicative of thick permafrost. This depth corresponds well to observations from a borehole drilled in the area in the late 1990s, which detected permafrost to a depth of about 100 meters (Clark and others, 2009). In contrast to the area of Fort Yukon, the Yukon River and its floodplain are not associated with deep resistive sediments, suggesting a lack of deep permafrost, at least within the depth range of the AEM mapping (fig. 3).

  8. Estimating aboveground biomass in the boreal forests of the Yukon River Basin, Alaska

    NASA Astrophysics Data System (ADS)

    Ji, L.; Wylie, B. K.; Nossov, D.; Peterson, B.; Waldrop, M. P.; McFarland, J.; Alexander, H. D.; Mack, M. C.; Rover, J. A.; Chen, X.

    2011-12-01

    Quantification of aboveground biomass (AGB) in Alaska's boreal forests is essential to accurately evaluate terrestrial carbon stocks and dynamics in northern high-latitude ecosystems. However, regional AGB datasets with spatially detailed information (<500 m) are not available for this extensive and remote area. Our goal was to map AGB at 30-m resolution for the boreal forests in the Yukon River Basin of Alaska using recent Landsat data and ground measurements. We collected field data in the Yukon River Basin from 2008 to 2010. Ground measurements included diameter at breast height (DBH) or basal diameter (BD) for live and dead trees and shrubs (>1 m tall), which were converted to plot-level AGB using allometric equations. We acquired Landsat Enhanced Thematic Mapper Plus (ETM+) images from the Web Enabled Landsat Data (WELD) that provides multi-date composites of top-of-atmosphere reflectance and brightness temperature for Alaska. From the WELD images, we generated a three-year (2008 - 2010) image composite for the Yukon River Basin using a series of compositing criteria including non-saturation, non-cloudiness, maximal normalize difference vegetation index (NDVI), and maximal brightness temperature. Airborne lidar datasets were acquired for two sub-regions in the central basin in 2009, which were converted to vegetation height datasets using the bare-earth digital surface model (DSM) and the first-return DSM. We created a multiple regression model in which the response variable was the field-observed AGB and the predictor variables were Landsat-derived reflectance, brightness temperature, and spectral vegetation indices including NDVI, soil adjusted vegetation index (SAVI), enhanced vegetation index (EVI), normalized difference infrared index (NDII), and normalized difference water index (NDWI). Principal component analysis was incorporated in the regression model to remedy the multicollinearity problems caused by high correlations between predictor variables

  9. Trace metal concentrations in snow from the Yukon River Basin, Alaska and Canada

    USGS Publications Warehouse

    Wang, B.; Gough, L.; Hinkley, T.; Garbarino, J.; Lamothe, P.

    2005-01-01

    We report here on metal concentrations in snow collected from the Yukon River basin. Atmospheric transport of metals and subsequent deposition is a known mechanism for introducing metals into the northern environment. Potential sources of airborne elements are locally generated terrestrial sources, locally derived anthropogenic sources, and long range atmospheric transport. Sites were distributed along the Yukon River corridor and within the southeastern, central, and western basin areas. Snow samples were taken in the spring of 2001 and 2002 when the snow pack was at its maximum. Total-depth composite samples were taken from pits using clean techniques. Mercury was analyzed using cold vapor atomic fluorescence spectrometry. All other elements were analyzed by inductively coupled plasma-mass spectrometry. In samples from remote sites, the concentration for selected metals ranged from: 0.015 - 0.34 ug/L for V, 0.01 - 0.22 ug/L for Ni, < 0.05 - 0.52 ug/L for Cu, 0.14 - 2.8 ug/L for Zn, 0.002 - 0.046 ug/L for Cd, 0.03 - 0.13 ug/L for Pb, 0.00041 - 0.0023 ug/L for filtered-Hg. Because the entire snow pack was sampled and there was no evidence of mid-season thaw, these concentrations represent the seasonal deposition. There was no significant difference in the seasonal deposition of V, Ni, Cu, Zn, Cd, and Pb at these sites between 2001 and 2002, and no north-south or east-west trend in concentrations. Samples taken from within communities, however, had significantly higher concentrations of V, Ni, Cu, Zn, and Cd in 2001, and Ni, Cu, and Pb in 2002 relative to the remote sites. Our data indicate that the atmospheric deposition of metals in the Yukon River basin is relatively uniform both spatially and temporally. However, communities have a measurable but variable effect on metal concentrations. Copyright ASCE 2005.

  10. Biomonitoring of Environmental Status and Trends (BEST) Program: Environmental contaminants and their effects on fish in the Yukon River Basin

    USGS Publications Warehouse

    Hinck, Jo Ellen; Bartish, Timothy M.; Blazer, Vicki; Denslow, Nancy D.; Gross, Tim S.; Myers, Mark S.; Anderson, Patrick J.; Orazio, Carl E.; Tillitt, Donald E.

    2004-01-01

    This project collected, examined, and analyzed 217 fish representing three species at 10 stations in the U.S. portion of the Yukon River Basin (YRB) from May to October 2002. Four sampling sites were located on the Yukon River; two were located on the Porcupine River, and one site was on each of the Ray, Tanana, Tolavana, and Innoko Rivers. Norther pike (Esox lucius), longnose sucker (Catostomus catostomus), and burbot (Lota lota) were weighed and measured, and examined in the field for external and internal lesions, and liver, spleen, and gonads were weighed to compute somatic indices. Selected tissues and fluids were collected and preserved for analysis of fish health and reproductive biomarkers. Composite samples of whole fish from each station were grouped by species and gender and analyzed for organochlorines and elemental contaminants and for dioxin-like activity using H4IIE rat hepatoma cell bioassay.

  11. Success in Outreach and Education Through a Partnership Approach Between Government and Grass Roots: The Yukon River Basin Water Quality Monitoring Program

    NASA Astrophysics Data System (ADS)

    Maracle, B. K.; Schuster, P. F.

    2008-12-01

    The U.S. Geological Survey (USGS) recently concluded a five-year water quality study (2001-2005) of the Yukon River and its major tributaries. One component of the study was to establish a water quality baseline providing a frame of reference to assess changes in the basin that may result from climate change. As the study neared its conclusion, the USGS began to foster a relationship with the Yukon River Inter-Tribal Watershed Council (YRITWC). The YRITWC was in the process of building a steward-based Yukon River water quality program. Both the USGS and the YRITWC recognized the importance of collaboration resulting in mutual benefits. Through the guidance, expertise, and training provided by the USGS, YRITWC developed and implemented a basin-wide water quality program. The YRITWC program began in March, 2006 utilizing USGS protocols, techniques, and in-kind services. To date, more than 300 samplings and field measurements at more than 25 locations throughout the basin (twice the size of California) have been completed by more than 50 trained volunteers. The Yukon River Basin baseline water quality database has been extended from 5 to 8 years due to the efforts of the YRITWC-USGS collaboration. Basic field measurements include field pH, specific conductance, dissolved oxygen, and water temperature. Samples taken for laboratory analyses include major ions, dissolved organic carbon, greenhouse gases, nutrients, and stable isotopes of hydrogen and oxygen, and selected trace elements. Field replicates and blanks were introduced into the program in 2007 for quality assurance. Building toward a long-term dataset is critical to understanding the effects of climate change on river basins. Thus, relaying the importance of long-term water-quality databases is a main focus of the training workshops. Consistencies in data populations between the USGS 5-year database and the YRITWC 3-year database indicate protocols and procedures made a successful transition. This reflects the

  12. Stratiform zinc-lead mineralization in Nasina assemblage rocks of the Yukon-Tanana Upland in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Bressler, Jason R.; Takaoka, Hidetoshi; Mortensen, James K.; Oliver, Douglas H.; Leventhal, Joel S.; Newberry, Rainer J.; Bundtzen, Thomas K.

    1998-01-01

    The Yukon-Tanana Upland of east-central Alaska and Yukon comprises thrust sheets of ductilely deformed metasedimentary and metaigneous rocks of uncertain age and origin that are overlain by klippen of weakly metamorphosed oceanic rocks of the Seventymile-Slide Mountain terrane, and intruded by post-kinematic Early Jurassic, Cretaceous and Tertiary granitoids. Metamorphosed continental margin strata in the Yukon-Tanana Upland of east-central Alaska are thought to be correlative, on the basis of stratigraphic similarities and sparse Mississippian U-Pb zircon and fossil ages (Mortensen, 1992), with middle Paleozoic metasedimentary and metavolcanic rocks in the eastern Alaska Range and in western and southeastern Yukon. Furthermore, rocks in the northern Yukon-Tanana Upland may correlate across the Tintina fault with unmetamorphosed counterparts in the Selwyn Basin (Murphy and Abbott, 1995). Volcanic-hosted (VMS) and sedimentary exhalative (sedex) massive sulfide occurrences are widely reported for these other areas (green-colored unit of fig. 1) but, as yet, have not been documented in the Alaskan part of the Yukon-Tanana Upland. Recent discoveries of VMS deposits in Devono-Mississippian metavolcanic rocks in the Finlayson Lake area of southeastern Yukon (Hunt, 1997) have increased the potential for finding VMS deposits in rocks of similar lithology and age in the Yukon-Tanana Upland of Alaska. Restoration of 450 km of early Tertiary dextral movement along the Tintina fault juxtaposes these two areas.

  13. Variation in the population structure of Yukon River chum and coho salmon: Evaluating the potential impact of localized habitat degradation

    USGS Publications Warehouse

    Olsen, J.B.; Spearman, William J.; Sage, G.K.; Miller, S.J.; Flannery, B.G.; Wenburg, J.K.

    2004-01-01

    We used microsatellite and mitochondrial DNA-restriction fragment length polymorphism (mtDNA-RFLP) analyses to test the hypothesis that chum salmon Oncorhynchus keta and coho salmon O. kisutch in the Yukon River, Alaska, exhibit population structure at differing spatial scales. If the hypothesis is true, then the risk of losing genetic diversity because of habitat degradation from a gold mine near a Yukon River tributary could differ between the two species. For each species, collections were made from two tributaries in both the Innoko and Tanana rivers, which are tributaries to the lower and middle Yukon River. The results revealed a large difference in the degree and spatial distribution of population structure between the two species. For chum salmon, the microsatellite loci (F-statistic [FST] = 0.021) and mtDNA (F ST = -0.008) revealed a low degree of interpopulation genetic diversity on a relatively large geographic scale. This large-scale population structure should minimize, although not eliminate, the risk of genetic diversity loss due to localized habitat degradation. For coho salmon, the microsatellites (FST = 0.091) and mtDNA (FST = 0.586) revealed a high degree of interpopulation genetic diversity on a relatively small geographic scale. This small-scale population structure suggests that coho salmon are at a relatively high risk of losing genetic diversity due to lo-calized habitat degradation. Our study underscores the importance of a multispecies approach for evaluating the potential impact of land-use activities on the genetic diversity of Pacific salmon.

  14. The Intersection of Environmental Variability, Policy, and Human Values: International Treaties, Yukon River Salmon, and Food Security in a Changing Arctic (Invited)

    NASA Astrophysics Data System (ADS)

    Gerlach, S.; Loring, P. A.; Murray, M. S.

    2009-12-01

    2009 was a particularly devastating year for rural communities of the Yukon River in Alaska. For a number of reasons, including annual variability in Chinook and Chum salmon runs, imperfect monitoring and information, “best practices” management decisions by regulatory agencies, and international treaty obligations related to conservation and total allowable catch allocation, the smokehouses and freezers of many Alaska Native families, particularly those in up-river communities in the Yukon Flats region, are empty; a problem that has prompted Alaska’s Governor Sean Parnell to ask the US Federal Government to declare a disaster. However, depending on whom you ask, this year’s management of these resources, which provide food security and enable self-reliance in rural communities, may be evaluated as a failure or as a success. How can we reconcile an institutional assessment that claims success as defined in terms of internationally-agreed upon conservation and escapement goals, with the negative economic and health impacts on communities? We use this case to illustrate how the whole Yukon River watershed and drainage, including Alaska and Canada, provides an elegant, geographic context for the discussion and analysis of the human dimensions of environmental change and regional sustainability. Policymakers have arguably gone to great lengths to reconcile competing ‘uses’ of the Yukon River, including commercial and subsistence uses as well as conservation goals, but while managers continue to strive to be ‘adaptive learners’ in their approach to balancing these goals, the impacts on rural communities are immediate and cumulative, synergistic, temporally and spatially scaled, and directly related to rural livelihoods, community health, well-being and sustainability. The cost of this ‘adaptive’ process may be too high, both for the ecosystem and for the people who live there. Are we asking too much of the Yukon River? Are we asking too much of the

  15. Source water controls on the character and origin of dissolved organic matter in streams of the Yukon River basin, Alaska

    Treesearch

    Jonathan A. O' Donnell; George R. Aiken; Evan S. Kane; Jeremy B. Jones

    2010-01-01

    Climate warming and permafrost degradation at high latitudes will likely impact watershed hydrology, and consequently, alter the concentration and character of dissolved organic carbon (DOC) in northern rivers. We examined seasonal variation of DOC chemistry in 16 streams of the Yukon River basin, Alaska. Our primary objective was to evaluate DOC chemical composition....

  16. Geomorphic Controls on Floodplain Soil Organic Carbon in the Yukon Flats, Interior Alaska, From Reach to River Basin Scales

    NASA Astrophysics Data System (ADS)

    Lininger, K. B.; Wohl, E.; Rose, J. R.

    2018-03-01

    Floodplains accumulate and store organic carbon (OC) and release OC to rivers, but studies of floodplain soil OC come from small rivers or small spatial extents on larger rivers in temperate latitudes. Warming climate is causing substantial change in geomorphic process and OC fluxes in high latitude rivers. We investigate geomorphic controls on floodplain soil OC concentrations in active-layer mineral sediment in the Yukon Flats, interior Alaska. We characterize OC along the Yukon River and four tributaries in relation to geomorphic controls at the river basin, segment, and reach scales. Average OC concentration within floodplain soil is 2.8% (median = 2.2%). Statistical analyses indicate that OC varies among river basins, among planform types along a river depending on the geomorphic unit, and among geomorphic units. OC decreases with sample depth, suggesting that most OC accumulates via autochthonous inputs from floodplain vegetation. Floodplain and river characteristics, such as grain size, soil moisture, planform, migration rate, and riverine DOC concentrations, likely influence differences among rivers. Grain size, soil moisture, and age of surface likely influence differences among geomorphic units. Mean OC concentrations vary more among geomorphic units (wetlands = 5.1% versus bars = 2.0%) than among study rivers (Dall River = 3.8% versus Teedrinjik River = 2.3%), suggesting that reach-scale geomorphic processes more strongly control the spatial distribution of OC than basin-scale processes. Investigating differences at the basin and reach scale is necessary to accurately assess the amount and distribution of floodplain soil OC, as well as the geomorphic controls on OC.

  17. Uranium isotopes (U-234/U-238) in rivers of the Yukon Basin (Alaska and Canada) as an aid in identifying water sources, with implications for monitoring hydrologic change in arctic regions

    USGS Publications Warehouse

    Kraemer, Thomas F.; Brabets, Timothy P.

    2012-01-01

    The ability to detect hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate change in high-latitude environments. Monitoring uranium isotopes (234U and 238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001–2005) has enhanced the ability to identify water sources to rivers, as well as detect flow changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate change.

  18. Ecology of invasive Melilotus albus on Alaskan glacial river floodplains

    USGS Publications Warehouse

    Conn, Jeff S.; Werdin-Pfisterer, Nancy R.; Beattie, Katherine L.; Densmore, Roseann V.

    2011-01-01

    Melilotus albus (white sweetclover) has invaded Alaskan glacial river floodplains. We measured cover and density of plant species and environmental variables along transects perpendicular to the Nenana, Matanuska, and Stikine Rivers to study interactions between M. albus and other plant species and to characterize the environment where it establishes. Melilotus albus was a pioneer species on recently disturbed sites and did not persist into closed canopy forests. The relationships between M. albus cover and density and other species were site-specific.Melilotus albus was negatively correlated with native species Elaeagnus commutata at the Nenana River, but not at the Matanuska River. Melilotus albus was positively correlated with the exotic species Crepis tectorumand Taraxacum officinale at the Matanuska River and T. officinale on the upper Stikine River. However, the high density of M. albus at a lower Stikine River site was negatively correlated with T. officinale and several native species including Lathyrus japonicus var. maritimus and Salix alaxensis. Glacial river floodplains in Alaska are highly disturbed and are corridors for exotic plant species movement. Melilotus albus at moderate to low densities may facilitate establishment of exotic species, but at high densities can reduce the cover and density of both exotic and native species.

  19. Climate-Driven Effects of Fire on Winter Habitat for Caribou in the Alaskan-Yukon Arctic

    PubMed Central

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas. PMID

  20. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic.

    PubMed

    Gustine, David D; Brinkman, Todd J; Lindgren, Michael A; Schmidt, Jennifer I; Rupp, T Scott; Adams, Layne G

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (-21%) than the Central Arctic herd that wintered primarily in the arctic tundra (-11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  1. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic

    USGS Publications Warehouse

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  2. Communicating Risk and Cultivating Resilience in Rural Alaskan Communities: A Multi-Disciplinary Approach to Flood Mitigation

    NASA Astrophysics Data System (ADS)

    Kontar, Y. Y.

    2014-12-01

    The increasing extent and vulnerability of technologically advanced society together with aspects of global climate change intensifies the frequency and severity of natural disasters. Every year, communities around the world face the devastating consequences of hazardous events, including loss of life, property and infrastructure damage, and environmental decline. Environmentally sound strategies have to be developed to minimize these consequences. However, hazard-prone areas differ geographically, climatically, and culturally. There is no a one-size-fits-all solution. Thus, it is crucial that future decision-makers not only know the conditions that make some natural Earth processes hazardous to people, but also understand how people perceive and adjust to potential natural hazards in their regions. In May 2013, an ice jam caused major flooding in Galena, a remote village in interior Alaska. Within two days, flooding destroyed nearly the entire region's infrastructure, and displaced over 400 residents. Almost a year later, a significant part of Galena's population was still evacuated in Fairbanks and other neighboring towns. The rebuilding holdup reflected the federal government's reluctance to spend millions of dollars an the area that may be destroyed again by the next flood. Massive floods inundated towns along the Yukon River before (e.g., Eagle in 2009 and Holycross in 1975), but people return to refurbish and again inhabit the same territories. Rivers have a significant importance to Alaskan rural communities. Not only do rivers provide food, drink, transportation, and in some cases arable land and irrigation, but they also carry cultural significance for the Native Alaskan people. The Galena case study provides a revealing example of challenges of communicating with and educating the public and policy makers about natural hazards.

  3. Lidar-based biomass assessment for the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Peterson, B.; Wylie, B. K.; Stoker, J.; Nossov, D.

    2010-12-01

    Climate change is expected to have a significant impact on high-latitude forests in terms of their ability to sequester carbon as expressed as pools of standing total biomass and soil organic matter. Above ground biomass is an important driver in ecosystem process models used to assess, predict, and understand climate change impacts. Therefore, it is of compelling interest to acquire accurate assessments of current biomass levels for these high-latitude forests, a particular challenge because of their vastness and remoteness. At this time, remote sensing is the only feasible method through which to acquire such assessments. In this study, the use of lidar data for estimating shrub and tree biomass for the Yukon Flats region of Alaska’s Yukon River Basin (YRB) is demonstrated. The lidar data were acquired in the late summer and fall of 2009 as were an initial set of field sampling data collected for training and validation purposes. The 2009 field campaigns were located near Canvasback Lake and Boot Lake in the YRB. Various tallies of biomass were calculated from the field data using allometric equations (Bond-Lamberty et al. 2002, Yarie et al. 2007, Mack et al. 2008). Additional field data were also collected during two 2010 field campaigns at different locations in the Yukon Flats. Linear regressions have been developed based on field-based shrub and tree biomass and various lidar metrics of canopy height calculated for the plots (900 m^2). A multiple linear regression performed at the plot level resulted in a strong relationship (R^2=0.88) between observed and predicted biomass at the plot level. The coefficients for this regression were used to generate a shrub and tree biomass map for the entire Yukon Flats study area covered by lidar. This biomass map will be evaluated using additional field data collected in 2010 as well as other remote sensing data sources. Furthermore, additional lidar metrics (e.g. height of median energy) are being derived from the raw

  4. Investigating the ancient landscape and Cenozoic drainage development of southern Yukon (Canada), through restoration modeling of the Cordilleran-scale Tintina Fault.

    NASA Astrophysics Data System (ADS)

    Hayward, N.; Jackson, L. E.; Ryan, J. J.

    2017-12-01

    This study of southern Yukon (Canada) challenges the notion that the landscape in the long-lived, tectonically active, northern Canadian Cordillera is implicitly young. The impact of Cenozoic displacement along the continental- scale Tintina Fault on the development of the Yukon River and drainage basins of central Yukon is investigated through geophysical and hydrological modeling of digital terrain model data. Regional geological evidence suggests that the age of the planation of the Yukon plateaus is at least Late Cretaceous, rather than Neogene as previously concluded, and that there has been little penetrative deformation or net incision in the region since the late Mesozoic. The Tintina Fault has been interpreted as having experienced 430 km of dextral displacement, primarily during the Eocene. However, the alignment of river channels across the fault at specific displacements, coupled with recent seismic events and related fault activity, indicate that the fault may have moved in stages over a longer time span. Topographic restoration and hydrological models show that the drainage of the Yukon River northwestward into Alaska via the ancestral Kwikhpak River was only possible at restored displacements of up to 50-55 km on the Tintina Fault. We interpret the published drainage reversals convincingly attributed to the effects of Pliocene glaciation as an overprint on earlier Yukon River reversals or diversions attributed to tectonic displacements along the Tintina Fault. At restored fault displacements of between 230 and 430 km, our models illustrate that paleo Yukon River drainage conceivably may have flowed eastward into the Atlantic Ocean via an ancestral Liard River, which was a tributary of the paleo Bell River system. The revised drainage evolution if correct requires wide-reaching reconsideration of surficial geology deposits, the flow direction and channel geometries of the region's ancient rivers, and importantly, exploration strategies of placer gold

  5. Airborne Imaging in the Yukon River Basin to Characterize SWOT Mission Phenomenology

    NASA Astrophysics Data System (ADS)

    Moller, D.; Pavelsky, T.; Arvesen, J. C.

    2015-12-01

    Remote sensing offers intriguing tools to track Arctic hydrology, but current techniques are largely limited to tracking either inundation or water surface elevation only. For the first time, the proposed Surface Water Ocean Topography (SWOT) satellite mission will provide regular, simultaneous observations of inundation extent and water level from space. SWOT is unique and distinct from precursor altimetry missions in some notable regards: 1) 100km+ of swath will provide complete ocean coverage, 2) in addition to the ocean product, land surface water will be mapped for storage measurement and discharge estimation and 3) Ka-band single-pass interferometry will produce the height measurements introducing a new measurement technique. This new approach introduces additional algorithmic, characterization and calibration/validation needs for which the Ka-band SWOT Phenomenology Airborne Radar (KaSPAR) was developed. In May 2015, AirSWOT (comprised of KaSPAR and a color infrared (CIR) high resolution aerial camera) was part of an intensive field campaign including observations of inundation extent and water level and in situ hydrologic measurements in two rivers and 20 lakes within the Yukon River Basin, Alaska. One goal is to explore the fundamental phenomenology of the SWOT measurement. This includes assessment of the effects of vegetation layover and attenuation, wind roughening and classification. Further KaSPAR-derived inundation extent will to be validated using a combination of ground surveys and coregistered CIR imagery. Ultimately, by combining measurements of changing inundation extent and water level between two collection dates, it will be possible to validate lake water storage variations against storage changes computed from in situ water levels and inundation area derived from AirSWOT. Our paper summarizes the campaign, the airborne and in situ measurements and presents some initial KaSPAR and CIR imagery from the Yukon flats region.

  6. Increased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogen

    USGS Publications Warehouse

    Walvoord, Michelle Ann; Striegl, Robert G.

    2007-01-01

    Arctic and subarctic watersheds are undergoing climate warming, permafrost thawing, and thermokarst formation resulting in quantitative shifts in surface water - groundwater interaction at the basin scale. Groundwater currently comprises almost one fourth of Yukon River water discharged to the Bering Sea and contributes 5-10% of the dissolved organic carbon (DOC) and nitrogen (DON) and 35-45% of the dissolved inorganic carbon (DIC) and nitrogen (DIN) loads. Long-term strearnflow records (>30 yrs) of the Yukon River basin indicate a general upward trend in groundwater contribution to streamflow of 0.7-0.9%/yr and no pervasive change in annual flow. We propose that the increases in groundwater contributions were caused predominately by climate warming and permafrost thawing that enhances infiltration and supports deeper flowpaths. The increased groundwater fraction may result in decreased DOC and DON and increased DIC and DIN export when annual flow remains unchanged.

  7. Kaltag fault, northern Yukon, Canada: Constraints on evolution of Arctic Alaska

    NASA Astrophysics Data System (ADS)

    Lane, Larry S.

    1992-07-01

    The Kaltag fault has been linked to several strike-slip models of evolution of the western Arctic Ocean. Hundreds of kilometres of Cretaceous-Tertiary displacement have been hypothesized in models that emplace Arctic Alaska into its present position by either left- or right-lateral strike slip. However, regional-scale displacement is precluded by new potential-field data. Postulated transform emplacement of Arctic Alaska cannot be accommodated by motion on the Kaltag fault or adjacent structures. The Kaltag fault of the northern Yukon is an eastward extrapolation of its namesake in west-central Alaska; however, a connection cannot be demonstrated. Cretaceous-Tertiary displacement on the Alaskan Kaltag fault is probably accommodated elsewhere.

  8. Mercury export from the Yukon River Basin and potential response to a changing climate

    USGS Publications Warehouse

    Schuster, P. F.; Striegl, Robert G.; Aiken, G. R.; Krabbenhoft, D. P.; Dewild, J. F.; Butler, K.; Kamark, B.; Dornblaser, M.

    2011-01-01

    We measured mercury (Hg) concentrations and calculated export and yield from the Yukon River Basin (YRB) to quantify Hg flux from a large, permafrost-dominated, high-latitude watershed. Exports of Hg averaged 4400 kg Hg yr–1. The average annual yield for the YRB during the study period was 5.17 μg m–2 yr–1, which is 3–32 times more than Hg yields reported for 8 other major northern hemisphere river basins. The vast majority (90%) of Hg export is associated with particulates. Half of the annual export of Hg occurred during the spring with about 80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic effects to biota. Dissolved and particulate organic carbon exports explained 81% and 50%, respectively, of the variance in Hg exports, and both were significantly (p < 0.001) correlated with water discharge. Recent measurements indicate that permafrost contains a substantial reservoir of Hg. Consequently, climate warming will likely accelerate the mobilization of Hg from thawing permafrost increasing the export of organic carbon associated Hg and thus potentially exacerbating the production of bioavailable methylmercury from permafrost-dominated northern river basins.

  9. Mercury export from the Yukon River Basin and potential response to a changing climate

    USGS Publications Warehouse

    Schuster, Paul F.; Striegl, Robert G.; Aiken, George R.; Krabbenhoft, David P.; DeWild, John F.; Butler, Kenna D.; Kamark, Ben; Dornblaser, Mark

    2011-01-01

    We measured mercury (Hg) concentrations and calculated export and yield from the Yukon River Basin (YRB) to quantify Hg flux from a large, permafrost-dominated, high-latitude watershed. Exports of Hg averaged 4400 kg Hg yr-1. The average annual yield for the YRB during the study period was 5.17 μg m-2 yr-1, which is 3–32 times more than Hg yields reported for 8 other major northern hemisphere river basins. The vast majority (90%) of Hg export is associated with particulates. Half of the annual export of Hg occurred during the spring with about 80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic effects to biota. Dissolved and particulate organic carbon exports explained 81% and 50%, respectively, of the variance in Hg exports, and both were significantly (p < 0.001) correlated with water discharge. Recent measurements indicate that permafrost contains a substantial reservoir of Hg. Consequently, climate warming will likely accelerate the mobilization of Hg from thawing permafrost increasing the export of organic carbon associated Hg and thus potentially exacerbating the production of bioavailable methylmercury from permafrost-dominated northern river basins.

  10. Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation

    USGS Publications Warehouse

    Ager, T.A.; Matthews, J.V.; Yeend, W.

    1994-01-01

    Gravels deposited by the ancestral Yukon River are preserved in terrace remnants on the margins of the Yukon River valley near the village of Circle in east-central Alaska. Plant fossils recovered from sandy silt lenses within these gravels include cones and needles of Picea and Larix and a variety of seeds. Seed types include several taxa which no longer grow in Alaska, such as Epipremnum, Prunus and Weigela. Pollen types recovered from these deposits represent tree and shrub taxa that grow in interior Alaska today, such as Picea, Larix, Betula and Alnus, as well as several taxa that no longer grow in interior Alaska today, such as Pinus, Tsuga, Abies and Corylus. Pollen of herb taxa identified include Gramineae, Cyperaceae, Caryophyllaceae, Compositae, Polemonium and Epilobium. The fossil flora from the gravels near Circle are similar and probably age-equivalent to the flora recovered from the Nenana Gravel in the Alaska Range 250 km to the south. Palynological and tectonic evidence summarized in this paper now suggests that the Nenana Gravel was deposited during the early and middle Pliocene. The presence of plant fossils of Tsuga, Abies, Pinus, Weigela and Prunus suggests that the mean annual temperature (MAT) of eastern interior Alaska during the early and middle Pliocene was perhaps 7-9??C warmer and less continental than today's MAT of -6.4??C. ?? 1994.

  11. Observations and Impacts of Permafrost Thaw in the Lower Yukon River Basin and Yukon Delta Region: the Importance of Local Knowledge

    NASA Astrophysics Data System (ADS)

    Herman-Mercer, N. M.; Elder, K.; Toohey, R.; Mutter, E. A.

    2015-12-01

    In regions of the arctic and subarctic baseline measurements of permafrost dynamics are lacking and scientific research can be especially expensive when remote sensing techniques are utilized. This research demonstrated the importance of local observations, a powerful tool for understanding landscape change, such as permafrost dynamics. Fifty-five interviews were recently conducted with community members in four villages of the lower Yukon River Basin and Yukon Delta to understand local environmental and landscape changes and the impacts these changes may be having on the lives and livelihoods of these communities. The interviews were semi-structured and focused on many climate and landscape change factors including knowledge of permafrost in their community or the surrounding landscape. All positive respondents stated that they believe the permafrost is thawing. The research revealed that residents of the arctic and subarctic interact with permafrost in a variety of ways. Some people utilize permafrost to store food resources and have found that they have to dig deeper presently than in their youth in order to find ground cold enough. Others are involved in digging graves and report encountering easier excavation in recent years. Subsistence hunters and gatherers travel long distances by snowmobile and boat, and have noticed slumping ground, eroding river banks and coast lines, as well as land that seems to be rising. Finally, all residents of the arctic and subarctic interact with permafrost in terms of the stability of their homes and other infrastructure. Many interview participants complained of their houses leaning and needing more frequent adjustment than in the past. Indigenous residents of the arctic and subarctic have intimate relationships with their landscape owing to their subsistence lifestyle and are also connected to the landscape of the past through the teachings of their elders. Further, arctic and subarctic communities will sustain the majority

  12. Chemical complexity and source of the White River Ash, Alaska and Yukon

    USGS Publications Warehouse

    Preece, S.J.; McGimsey, Robert G.; Westgate, J.A.; Pearce, N.J.G.; Hartmann, W.K.; Perkins, W.T.

    2014-01-01

    The White River Ash, a prominent stratigraphic marker bed in Alaska (USA) and Yukon (Canada), consists of multiple compositional units belonging to two geochemical groups. The compositional units are characterized using multiple criteria, with combined glass and ilmenite compositions being the best discriminators. Two compositional units compose the northern group (WRA-Na and WRA-Nb), and two units are present in the eastern group (WRA-Ea and the younger, WRA-Eb). In the proximal area, the ca. 1900 yr B.P. (Lerbekmo et al., 1975) WRA-Na displays reverse zoning in the glass phase and systematic changes in ilmenite composition and estimated oxygen fugacity from the base to the top of the unit. The eruption probably tapped different magma batches or bodies within the magma reservoir with limited mixing or mingling between them. The 1147 cal yr B.P. (calibrated years, approximately equivalent to calendric years) (Clague et al., 1995) WRA-Ea eruption is only weakly zoned, but pumices with different glass compositions are present, along with gray and white intermingled glass in individual pumice clasts, indicating the presence of multiple magmatic bodies or layers. All White River Ash products are high-silica adakites and are sourced from the Mount Churchill magmatic system.

  13. Carbon export and cycling by the Yukon, Tanana, and Porcupine rivers, Alaska, 2001-2005

    USGS Publications Warehouse

    Striegl, Robert G.; Dornblaser, Mark M.; Aiken, George R.; Wickland, Kimberly P.; Raymond, Peter A.

    2007-01-01

    Loads and yields of dissolved and particulate organic and inorganic carbon (DOC, POC, DIC, PIC) were measured and modeled at three locations on the Yukon River (YR) and on the Tanana and Porcupine rivers (TR, PR) in Alaska during 2001–2005. Total YR carbon export averaged 7.8 Tg C yr−1, 30% as OC and 70% as IC. Total C yields (0.39–1.03 mol C m−2 yr−1) were proportional to water yields (139–356 mm yr−1; r2 = 0.84) at all locations. Summer DOC had an aged component (fraction modern (FM) = 0.94–0.97), except in the permafrost wetland‐dominated PR, where DOC was modern. POC had FM = 0.63–0.70. DOC had high concentration, high aromaticity, and high hydrophobic content in spring and low concentration, low aromaticity, and high hydrophilic content in winter. About half of annual DOC export occurred during spring. DIC concentration and isotopic composition were strongly affected by dissolution of suspended carbonates in glacial meltwater during summer.

  14. Environmental contaminants in fish and their associated risk to piscivorous wildlife in the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Hinck, J.E.; Schmitt, C.J.; Echols, K.R.; May, T.W.; Orazio, C.E.; Tillitt, D.E.

    2006-01-01

    Organochlorine chemical residues and elemental contaminants were measured in northern pike (Esox lucius), longnose sucker (Catostomus catostomus), and burbot (Lota lota) from 10 sites in the Yukon River Basin (YRB) during 2002. Contaminant concentrations were compared to historical YRB data and to toxicity thresholds for fish and piscivorous wildlife from the scientific literature. A risk analysis was conducted to screen for potential hazards to piscivorous wildlife for contaminants that exceeded literature-based toxicity thresholds. Concentrations of total DDT (sum of p,p???-homologs; 1.09-13.6 ng/g), total chlordane (0.67-7.5 ng/g), dieldrin (<0.16-0.6 ng/g), toxaphene (<11-34 ng/g), total PCBs (<20-87 ng/g), TCDD-EQ (???1.7 pg/g), arsenic (0.03-1.95 ??g/g), cadmium (<0.02-0.12 ??g/g), copper (0.41-1.49 ??g/g), and lead (<0.21-0.27 ??g/g) did not exceed toxicity thresholds for growth and reproduction in YRB fish. Concentrations of mercury (0.08-0.65 ??g/g), selenium (0.23-0.85 ??g/g), and zinc (11-56 ??g/g) exceeded toxicity thresholds in one or more samples and were included in the risk analysis for piscivorous wildlife. No effect hazard concentrations (NEHCs) and low effect hazard concentrations (LEHCs), derived from literature-based toxicity reference values and avian and mammalian life history parameters, were calculated for mercury, selenium, and zinc. Mercury concentrations in YRB fish exceeded the NEHCs for all bird and small mammal models, which indicated that mercury concentrations in fish may represent a risk to piscivorous wildlife throughout the YRB. Low risk to piscivorous wildlife was associated with selenium and zinc concentrations in YRB fish. Selenium and zinc concentrations exceeded the NEHCs and LEHCs for only the small bird model. These results indicate that mercury should continue to be monitored and assessed in Alaskan fish and wildlife. ?? 2006 Springer Science+Business Media, Inc.

  15. Dissolved Organic Carbon in the Yukon, Tanana and Porcupine Rivers, Alaska

    NASA Astrophysics Data System (ADS)

    Aiken, G. R.; Striegl, R. G.; Wickland, K. P.; Dornblaser, M. M.; Raymond, P. A.

    2006-12-01

    The spatial and temporal variability of dissolved organic carbon (DOC) in the Yukon River (YR) and two major tributaries, the Porcupine River (PR), a black water river draining a watershed almost entirely underlain by permafrost, and the Tanana River (TR), a glacial dominated river, are being studied to better define processes controlling DOC in these systems. Five-year seasonal averages indicate DOC concentrations follow the discharge hydrograph, with highest daily and seasonal flux occurring during spring in YR and PR and during summer-autumn in TR. Largest DOC concentrations and specific UV absorption (SUVA) values, a measure of aromatic carbon content of the DOC and an indicator of DOC source, occurred at all locations during spring snowmelt. Lowest DOC concentration and SUVA occurred during low-flow in winter due to greatly reduced contributions of soil organic matter and to relatively greater influences of ground water. While all sites had comparable DOC concentration during winter, DOC concentration was greatest at PR during spring and summer-autumn, whereas TR had the lowest average DOC and SUVA values. Within the YR, average DOC concentration and SUVA values in spring and summer-autumn increase downriver due to contributions from organic carbon rich tributaries, such as PR, that increase in number and significance as the river flows through Alaska. Most the DOC in each system was comprised of hydrophobic organic acids (HPOA) derived from terrestrial vegetation. During winter, the hydrophilic fraction, determined to be the most biodegradable, was a larger percentage of the DOC than during spring-autumn. During spring, HPOA concentration and SUVA increased significantly at all sites, suggesting that most DOC in spring is derived from terrestrial organic matter that was frozen on the land surface over winter. During spring-autumn, PR had the largest concentration of HPOA and TR had the least. Like DOC concentration, HPOA concentration and SUVA increased down

  16. Optical and size characterization of dissolved organic matter from the lower Yukon River

    NASA Astrophysics Data System (ADS)

    Guo, L.; Lin, H.

    2017-12-01

    The Arctic rivers have experienced significant climate and environmental changes over the last several decades and their export fluxes and environmental fate of dissolved organic matter (DOM) have received considerable attention. Monthly or bimonthly water samples were collected from the Yukon River, one of the Arctic rivers, between July 2004 and September 2005 for size fractionation to isolate low-molecular-weight (LMW, <1 kDa) and high-molecular-weight (HMW, >1 kDa) DOM. The freeze-dried HMW-DOM was then characterized for their optical properties using fluorescence spectroscopy and colloidal size spectra using asymmetrical flow field-flow fractionation techniques. Ratios of biological index (BIX) to humification index (HIX) show a seasonal change, with lower values in river open seasons and higher values under the ice, and the influence of rive discharge. Three major fluorescence DOM components were identified, including two humic-like components (Ex/Em at 260/480 nm and 250/420 nm, respectively) and one protein-like component (Ex/Em=250/330). The ratio of protein-like to humic-like components was broadly correlated with discharge, with low values during spring freshet and high values under the ice. The relatively high protein-like/humic-like ratio during the ice-covered season suggested sources from macro-organisms and/or ice-algae. Both protein-like and humic-like colloidal fluorophores were partitioned mostly in the 1-5 kDa size fraction although the protein-like fluorophores in some samples also contained larger colloidal size. The relationship between chemical/biological reactivity and size/optical characteristics of DOM needs to be further investigated.

  17. Evaluation of three gears for sampling spawning populations of rainbow trout in a large Alaskan river

    USGS Publications Warehouse

    Schwanke, C.J.; Hubert, W.A.

    2004-01-01

    Alternatives to electrofishing are needed for sampling sexually mature rainbow trout Oncorhynchus mykiss during the spawning season in large Alaskan rivers. We compared hook and line, beach seining, and actively fished gill nets as sampling tools. Beach seining and active gill netting yielded similar catch rates, length frequencies, and sex ratios of sexually mature fish. Hook-and-line sampling was less effective, with a lower catch rate and selectivity for immature fish and sexually mature females. We conclude that both beach seining and active gill netting can serve as alternatives to electrofishing for sampling sexually mature rainbow trout stocks during the spawning season in large rivers with stable spring flows and spawning areas with few snags.

  18. The Indigenous Observation Network: Collaborative, Community-Based Monitoring in the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Herman-Mercer, N. M.; Mutter, E. A.; Wilson, N. J.; Toohey, R.; Schuster, P. F.

    2017-12-01

    The Indigenous Observation Network (ION) is a collaborative Community-Based Monitoring (CBM) program with both permafrost and water-quality monitoring components operating in the Yukon River Basin (YRB) of Alaska and Canada. ION is jointly facilitated by the Yukon River Inter-Tribal Watershed Council (YRITWC), an indigenous non-profit organization, and the US Geological Survey (USGS), a federal agency. The YRB is the fourth largest drainage basin in North America encompassing 855,000 square kilometers in northwestern Canada and central Alaska and is essential to the ecosystems of the Bering and Chuckchi Seas. Water is also fundamental to the subsistence and culture of the 76 Tribes and First Nations that live in the YRB providing sustenance in the form of drinking water, fish, wildlife, and vegetation. Despite the ecological and cultural significance of the YRB, the remote geography of sub-Arctic and Arctic Alaska and Canada make it difficult to collect scientific data in these locations and led to a lack of baseline data characterizing this system until recently. In response to community concerns about the quality of the YR and a desire by USGS scientists to create a long term water-quality database, the USGS and YRITWC collaborated to create ION in 2005. Surface water samples are collected by trained community technicians from Tribal Environmental Programs or First Nation Lands and Resources staff from over 35 Alaska Native Tribes and First Nations that reside along the YR and/or one of the major tributaries. Samples are analyzed at USGS laboratories in Boulder, CO and results are disseminated to participating YRB communities and the general public. This presentation will focus on the factors that have enabled the longevity and success of this program over the last decade, as well as the strategies ION uses to ensure the credibility of the data collected by community members and best practices that have facilitated the collection of surface water data in remote

  19. Synchronous cycling of Ichthyophoniasis with Chinook salmon density revealed during the annual Yukon River spawning migration

    USGS Publications Warehouse

    Zuray, Stanley; Kocan, Richard; Hershberger, Paul

    2012-01-01

    Populations of Chinook salmon Oncorhynchus tshawytscha in the Yukon River declined by more than 57% between 2003 and 2010, probably the result of a combination of anthropogenic and environmental factors. One possible contributor to this decline is Ichthyophonus, a mesomycetozoan parasite that has previously been implicated in significant losses of fish, including Chinook salmon. A multiyear epidemiological study of ichthyophoniasis in the Yukon River revealed that disease prevalence and Chinook salmon population abundance increased and decreased simultaneously (i.e., were concordant) from 1999 to 2010. The two values rose and fell synchronously 91% of the time for female Chinook salmon and 82% of the time for males; however, there was no significant correlation between Ichthyophonus prevalence and population abundance. This synchronicity might be explained by a single factor, such as a prey item that is critical to Chinook salmon survival as well as a source of Ichthyophonus infection. The host–parasite relationship between Ichthyophonus and migrating Chinook salmon from 2004 to 2010 was similar to that reported for the previous 5 years. During 2004–2010, overall disease prevalence was significantly higher among females (21%) than among males (8%), increased linearly with fish length for both males and females, and increased in both sexes as the fish progressed upriver. These regularly occurring features of host–parasite dynamics confirm a stable base of transmission for Ichthyophonus. However, from 2003 to 2010, disease prevalence decreased from 30% to just 8% in males and from 45% to 9% in females, paralleling a similar decline in Chinook salmon abundance during the same period. These findings may help clarify questions regarding the complex host–parasite dynamics that occur in marine species such as herrings Clupea spp., which have less well-defined population structures.

  20. Geologic Map of the Yukon-Koyukuk Basin, Alaska

    USGS Publications Warehouse

    Patton, William W.; Wilson, Frederic H.; Labay, Keith A.; Shew, Nora B.

    2009-01-01

    This map and accompanying digital files represent part of a systematic effort to release geologic data for the United States in a uniform manner. All the geologic data in this series will be published as parts of the U.S. Geological Survey Data Series. The geologic data in this series have been compiled from a wide variety of sources, ranging from state and regional geologic maps to large-scale field mapping. The data are presented for use at a nominal scale of 1:500,000, although individual datasets may contain data suitable for use at larger scales. The metadata associated with each release will provide more detailed information on sources and appropriate scales for use. Associated attribute databases accompany the spatial database of the geology and are uniformly structured for ease in developing regional- and national-scale maps. The 1:500,000-scale geologic map of the Yukon-Koyukuk Basin, Alaska, covers more than 200,000 square kilometers of western Alaska or nearly 15 percent of the total land area of the state. It stretches from the Brooks Range on the north to the Kuskokwim River and lower reaches of the Yukon River on the south and from Kotzebue Sound, Seward Peninsula, and Norton Sound on the west to the Yukon-Tanana Uplands and Tanana-Kuskokwim Lowlands on the east. It includes not only the northern and central part of the basin, but also the lands that border the basin. The area is characterized by isolated clusters of hills and low mountain ranges separated by broad alluviated interior and coastal lowlands. Most of the lowlands, except those bordering Kotzebue Sound and Norton Sound, support a heavy vegetation cover. Exposures of bedrock are generally limited to rubble-strewn ridgetops and to cutbanks along the rivers. The map of the Yukon-Koyukuk Basin was prepared largely from geologic field data collected between 1953 and 1988 by the U.S. Geological Survey and published as 1:250,000-scale geologic quadrangle maps. Additional data for parts of the

  1. Arctic-Yukon-Kuskokwim Salmon Research and Restoration Plan

    USGS Publications Warehouse

    2006-01-01

    The Arctic-Yukon-Kuskokwim Sustainable Salmon Initiative (AYK SSI) is an innovative partnership between public and private institutions which provides a forum for non-governmental organizations and state and federal agencies to cooperatively identify and address salmon research and restoration needs. The affected region encompasses over 40% of the State of Alaska; the AYK region includes the watersheds of the Norton Sound region up to and including the village of Shishmaref, the Yukon River Watershed within Alaska, and the Kuskokwim River Watershed (including the coastal watersheds north of Cape Newenham), plus the Bering Sea marine ecosystem. The AYK SSI is a response to disastrously low salmon returns to western Alaska in the late 1990s and early 2000s, which created numerous hardships for the people and communities that depend heavily on the salmon fishery. Some stocks in the region have been in a decline for more than a decade and a half, leading to severe restrictions on commercial and subsistence fisheries. The first step for the AYK SSI has been to collaboratively develop and implement a comprehensive research plan to understand the causes of the declines and recoveries of AYK salmon.

  2. A whole ecosystem approach to studying climate change in interior Alaska

    USGS Publications Warehouse

    Riggins, Susan; Striegl, Robert G.; McHale, Michael

    2011-01-01

    Yukon River Basin Principal Investigators Workshop; Portland, Oregon, 18-20 January 2011; High latitudes are known to be particularly susceptible to climate warming, leading to an emphasis of field and modeling research on arctic regions. Subarctic and boreal regions such as the Yukon River Basin (YRB) of interior Alaska and western Canada are less well studied, although they encompass large areas that are vulnerable to changes in forest composition, permafrost distribution, and hydrology. There is an urgent need to understand the resiliency and vulnerability of these complex ecosystems as well as their feedbacks to the global climate system. Consequently, U.S. Geological Survey scientists, with other federal agency, university, and private industry partners, is focusing subarctic interdisciplinary studies on the Beaver Creek Wild and Scenic River watershed (http://www.blm.gov/pgdata/content/ak/en/prog/nlcs/beavercrk_nwsr.html) and Yukon Flats National Wildlife Refuge (http://yukonflats.fws.gov/) in the YRB, south and west of Fort Yukon, Alaska. These areas are national treasures of wetlands, lakes, and uplands that support large populations of wildlife and waterfowl and are home to vibrant native Alaskan communities that depend on the area for a subsistence lifestyle.

  3. Estimations of evapotranspiration and water balance with uncertainty over the Yukon River Basin

    USGS Publications Warehouse

    Yuan, Wenping; Liu, Shuguang; Liang, Shunlin; Tan, Zhengxi; Liu, Heping; Young, Claudia

    2012-01-01

    In this study, the revised Remote Sensing-Penman Monteith model (RS-PM) was used to scale up evapotranspiration (ET) over the entire Yukon River Basin (YRB) from three eddy covariance (EC) towers covering major vegetation types. We determined model parameters and uncertainty using a Bayesian-based method in the three EC sites. The 95 % confidence interval for the aggregate ecosystem ET ranged from 233 to 396 mm yr−1 with an average of 319 mm yr−1. The mean difference between precipitation and evapotranspiration (W) was 171 mm yr−1 with a 95 % confidence interval of 94–257 mm yr−1. The YRB region showed a slight increasing trend in annual precipitation for the 1982–2009 time period, while ET showed a significant increasing trend of 6.6 mm decade−1. As a whole, annual W showed a drying trend over YRB region.

  4. Signals of large scale climate drivers, hatchery enhancement, and marine factors in Yukon River Chinook salmon survival revealed with a Bayesian life history model.

    PubMed

    Cunningham, Curry J; Westley, Peter A H; Adkison, Milo D

    2018-05-18

    Understanding how species might respond to climate change involves disentangling the influence of co-occurring environmental factors on population dynamics, and is especially problematic for migratory species like Pacific salmon that move between ecosystems. To date, debate surrounding the causes of recent declines in Yukon River Chinook salmon (Oncorhynchus tshawytscha) abundance has centered on whether factors in freshwater or marine environments control variation in survival, and how these populations at the northern extremity of the species range will respond to climate change. To estimate the effect of factors in marine and freshwater environments on Chinook salmon survival, we constructed a stage-structured assessment model that incorporates the best available data, estimates incidental marine bycatch mortality in trawl fisheries, and uses Bayesian model selection methods to quantify support for alternative hypotheses. Models fitted to two index populations of Yukon River Chinook salmon indicate that processes in the nearshore and marine environments are the most important determinants of survival. Specifically, survival declines when ice leaves the Yukon River later in the spring, increases with wintertime temperature in the Bering Sea, and declines with the abundance of globally enhanced salmon species consistent with competition at sea. In addition, we found support for density-dependent survival limitations in freshwater but not marine portions of the life cycle, increasing average survival with ocean age, and age-specific selectivity of bycatch mortality in the Bering Sea. This study underscores the utility of flexible estimation models capable of fitting multiple data types and evaluating mortality from both natural and anthropogenic sources in multiple habitats. Overall, these analyses suggest that mortality at sea is the primary driver of population dynamics, yet under a warming climate Chinook salmon populations at the northern extent of the species

  5. A 2,000-mile partnership with the USGS, Kayaks down the Yukon

    USGS Publications Warehouse

    Schuster, P.; Reddy, M.

    2003-01-01

    Early in 2001, Bill Barber and Jay Klinck, avid kayakers and scientists, began planning a northern expedition that would take them across more than 2,000 miles of mostly untamed wilderness along the Yukon River. At the same time, USGS scientists were making plans to study the last, unregulated great river in North America, spanning one of the largest and most diverse ecosystems in the world. Soon, the paths of kayakers and scientists would cross.

  6. Source water controls on the character and origin of dissolved organic matter in streams of the Yukon River basin, Alaska

    USGS Publications Warehouse

    O'Donnell, Jonathan A.; Aiken, George R.; Kane, Evan S.; Jones, Jeremy B.

    2010-01-01

    Climate warming and permafrost degradation at high latitudes will likely impact watershed hydrology, and consequently, alter the concentration and character of dissolved organic carbon (DOC) in northern rivers. We examined seasonal variation of DOC chemistry in 16 streams of the Yukon River basin, Alaska. Our primary objective was to evaluate the relationship between source water (shallow versus deep groundwater flow paths) and DOC chemical composition. Using base cation chemistry and principal component analysis, we observed high contributions of deep groundwater to glacial and clearwater streams, whereas blackwater streams received larger contributions from shallow groundwater sources. DOC concentration and specific ultraviolet absorbance peaked during spring snowmelt in all streams, and were consistently higher in blackwater streams than in glacial and clearwater streams. The hydrophobic acid fraction of DOC dominated across all streams and seasons, comprising between 35% and 56% of total DOC. The hydrophilic acid fraction of DOC was more prominent in glacial (23% ± 3%) and clearwater streams (19% ± 1%) than in blackwater streams (16% ± 1%), and was enriched during winter base flow (29% ± 1%) relative to snowmelt and summer base flow. We observed that an increase in the contribution of deep groundwater to streamflow resulted in decreased DOC concentration, aromaticity, and DOC-to-dissolved organic nitrogen ratio, and an increase in the proportion of hydrophilic acids relative to hydrophobic acids. Our findings suggest that future permafrost degradation and higher contributions of groundwater to streamflow may result in a higher fraction of labile DOM in streams of the Yukon basin.

  7. Dissolved nitrogen seasonal dynamics in Alaskan Arctic streams & rivers

    NASA Astrophysics Data System (ADS)

    Khosh, M. S.; McClelland, J. W.; Douglas, T. A.; Jacobson, A. D.; Barker, A. J.; Lehn, G. O.

    2011-12-01

    Over the coming century, continued warming in the Arctic is expected to bring about many changes to the region including altered precipitation regimes, earlier snowmelt, and degradation of permafrost. These alterations are likely to modify the hydrology within the region, including changes in the quantity, seasonality, and flow paths of water; all of which may impact biogeochemical processes within Arctic catchments. The anticipated responses to warming in the Arctic are likely to become most apparent during the spring snowmelt period, and in the late summer to early fall when the seasonally-thawed active layer reaches its maximum depth. While our knowledge of the seasonal dynamics of water-borne constituents in Arctic rivers is improving, the spring snowmelt and the late summer/early fall are times of the year that Arctic rivers have historically been under sampled. An improved understanding of the mechanisms that control the seasonal variability of water chemistry may help us to better understand how these systems will respond to further warming. Between May and October of 2009 and 2010 we collected surface water samples from six different rivers/streams in the Alaskan Arctic, with particular emphasis placed on sampling during the spring snowmelt and during the late summer until fall freeze-up. These rivers were selected because they represent end-member physical characteristics ranging from high gradient rivers draining predominantly bedrock to low gradient rivers draining predominantly tundra. The catchments of all six rivers are underlain by continuous permafrost and range in size from 1.6 km2 to 610 km2. Samples were analyzed for total dissolved nitrogen (TDN), nitrate (NO3-), and ammonium (NH4+). Dissolved organic nitrogen (DON) was calculated as [TDN] - [NO3-] - [NH4+]. TDN concentrations exhibited maxima in the spring and fall, but the prevailing forms of nitrogen differed markedly between the early and late periods. There were also marked differences

  8. Educational Psychology in Yukon

    ERIC Educational Resources Information Center

    Bradford, Charlene T.; Kroeker, Sharon D. L.

    2016-01-01

    Directly employed by the territorial government, Yukon's educational psychologists are moving away from "refer-test-place" services by actively clarifying a broader scope of practice within a non-categorical model of special education services. Yukon's educational psychologists provide a variety of services, such as consultation,…

  9. Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska

    USGS Publications Warehouse

    Spencer, R.G.M.; Aiken, G.R.; Butler, K.D.; Dornblaser, M.M.; Striegl, Robert G.; Hernes, P.J.

    2009-01-01

    The quality and quantity of dissolved organic matter (DOM) exported by Arctic rivers is known to vary with hydrology and this exported material plays a fundamental role in the biogeochemical cycling of carbon at high latitudes. We highlight the potential of optical measurements to examine DOM quality across the hydrograph in Arctic rivers. Furthermore, we establish chromophoric DOM (CDOM) relationships to dissolved organic carbon (DOC) and lignin phenols in the Yukon River and model DOC and lignin loads from CDOM measurements, the former in excellent agreement with long-term DOC monitoring data. Intensive sampling across the historically under-sampled spring flush period highlights the importance of this time for total export of DOC and particularly lignin. Calculated riverine DOC loads to the Arctic Ocean show an increase from previous estimates, especially when new higher discharge data are incorporated. Increased DOC loads indicate decreased residence times for terrigenous DOM in the Arctic Ocean with important implications for the reactivity and export of this material to the Atlantic Ocean. Citation: Spencer, R. G. M., G. R. Aiken, K. D. Butler, M. M. Dornblaser, R. G. Striegl, and P. J. Hernes (2009), Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska, Geophys. Res. Lett., 36, L06401, doi:10.1029/ 2008GL036831. Copyright 2009 by the American Geophysical Union.

  10. Nitrogen cycling processes and microbial community composition in bed sediments in the Yukon River at Pilot Station

    USGS Publications Warehouse

    Repert, Deborah A.; Underwood, Jennifer C.; Smith, Richard L.; Song, Bongkeun

    2014-01-01

    Information on the contribution of nitrogen (N)-cycling processes in bed sediments to river nutrient fluxes in large northern latitude river systems is limited. This study examined the relationship between N-cycling processes in bed sediments and N speciation and loading in the Yukon River near its mouth at the Bering Sea. We conducted laboratory bioassays to measure N-cycling processes in sediment samples collected over distinct water cycle seasons. In conjunction, the microbial community composition in the bed sediments using genes involved in N-cycling (narG, napA, nosZ, and amoA) and 16S rRNA gene pyrosequences was examined. Temporal variation was observed in net N mineralization, nitrate uptake, and denitrification rate potentials and correlated strongly with sediment carbon (C) and extractable N content and microbial community composition rather than with river water nutrient concentrations. The C content of the bed sediment was notably impacted by the spring flood, ranging from 1.1% in the midst of an ice-jam to 0.1% immediately after ice-out, suggesting a buildup of organic material (OM) prior to scouring of the bed sediments during ice break up. The dominant members of the microbial community that explained differences in N-processing rates belonged to the genera Crenothrix,Flavobacterium, and the family of Comamonadaceae. Our results suggest that biogeochemical processing rates in the bed sediments appear to be more coupled to hydrology, nutrient availability in the sediments, and microbial community composition rather than river nutrient concentrations at Pilot Station.

  11. ALASKAN RTMA GRAPHICS

    Science.gov Websites

    Alaskan RTMA Graphics This page displays Alaskan Real-Time Mesoscale Analyses and compares them to DISCLAIMER: The Alaskan Real-Time Mesoscale Analysis tool is in its developmental stage, and there is much

  12. Yukon Training Strategy. Training for the Future.

    ERIC Educational Resources Information Center

    Yukon Dept. of Education, White Horse.

    This document was created as part of "Yukon 2000," a Yukon government initiative for steering social and economic growth. The expressed intent of the training strategy is to direct government efforts toward preparing people for existing and potential employment in the Yukon. In some areas, the strategy confirms program directions already…

  13. Indigenous observations of climate change in the Lower Yukon River Basin, Alaska

    USGS Publications Warehouse

    Herman-Mercer, Nicole M.; Schuster, Paul F.; Maracle, Karonhiakt'tie

    2011-01-01

    Natural science climate change studies have led to an overwhelming amount of evidence that the Arctic and Subarctic are among the world's first locations to begin experiencing climate change. Indigenous knowledge of northern regions is a valuable resource to assess the effects of climate change on the people and the landscape. Most studies, however, have focused on coastal Arctic and Subarctic communities with relatively little focus on inland communities. This paper relates the findings from fieldwork conducted in the Lower Yukon River Basin of Alaska in the spring of 2009. Semi-structured interviews were conducted with hunters and elders in the villages of St. Mary's and Pitka's Point, Alaska to document observations of climate change. This study assumes that scientific findings and indigenous knowledge are complementary and seeks to overcome the false dichotomy that these two ways of knowing are in opposition. The observed changes in the climate communicated by the hunters and elders of St. Mary's and Pitka's Point, Alaska are impacting the community in ways ranging from subsistence (shifting flora and fauna patterns), concerns about safety (unpredictable weather patterns and dangerous ice conditions), and a changing resource base (increased reliance on fossil fuels). Here we attempt to address the challenges of integrating these two ways of knowing while relating indigenous observations as described by elders and hunters of the study area to those described by scientific literature.

  14. Bowhead whale behavior in relation to seismic exploration, Alaskan Beaufort Sea, Autumn 1981. Study report (Final)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fraker, M.A.; Ljungblad, D.K.; Richardson, W.J.

    1985-10-01

    Behavior of bowhead whales (Balsena mysticetus) in the eastern part of the Alaskan Beaufort Sea or near the Alaska/Yukon border was observed from a circling turbine-powered Goose aircraft on 10 dates from 12 September to 5 October 1981. On three of these dates, the whales were exposed t, noise impulses from seismic vessels 13 km or more away. Some behavioral data were acquired. In both the presence and the absence of seismic impulses, most bowheads appeared to be feeding in the water column, although slow travel and active socializing were sometimes detected. Sonobuoys detected bowhead calls both in the presencemore » and the absence of seismic impulses. There was no clear evidence of unusual behavior in the presence of seismic impulses.« less

  15. Origin of last-glacial loess in the western Yukon-Tanana Upland, central Alaska, USA

    USGS Publications Warehouse

    Muhs, Daniel; Pigati, Jeffrey S.; Budahn, James R.; Skipp, Gary L.; Bettis, E. Arthur; Jensen, Britta

    2018-01-01

    Loess is widespread over Alaska, and its accumulation has traditionally been associated with glacial periods. Surprisingly, loess deposits securely dated to the last glacial period are rare in Alaska, and paleowind reconstructions for this time period are limited to inferences from dune orientations. We report a rare occurrence of loess deposits dating to the last glacial period, ~19 ka to ~12 ka, in the Yukon-Tanana Upland. Loess in this area is very coarse grained (abundant coarse silt), with decreases in particle size moving south of the Yukon River, implying that the drainage basin of this river was the main source. Geochemical data show, however, that the Tanana River valley to the south is also a likely distal source. The occurrence of last-glacial loess with sources to both the south and north is explained by both regional, synoptic-scale winds from the northeast and opposing katabatic winds that could have developed from expanded glaciers in both the Brooks Range to the north and the Alaska Range to the south. Based on a comparison with recent climate modeling for the last glacial period, seasonality of dust transport may also have played a role in bringing about contributions from both northern and southern sources.

  16. Spatially explicit estimation of aboveground boreal forest biomass in the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Ji, Lei; Wylie, Bruce K.; Brown, Dana R. N.; Peterson, Birgit E.; Alexander, Heather D.; Mack, Michelle C.; Rover, Jennifer R.; Waldrop, Mark P.; McFarland, Jack W.; Chen, Xuexia; Pastick, Neal J.

    2015-01-01

    Quantification of aboveground biomass (AGB) in Alaska’s boreal forest is essential to the accurate evaluation of terrestrial carbon stocks and dynamics in northern high-latitude ecosystems. Our goal was to map AGB at 30 m resolution for the boreal forest in the Yukon River Basin of Alaska using Landsat data and ground measurements. We acquired Landsat images to generate a 3-year (2008–2010) composite of top-of-atmosphere reflectance for six bands as well as the brightness temperature (BT). We constructed a multiple regression model using field-observed AGB and Landsat-derived reflectance, BT, and vegetation indices. A basin-wide boreal forest AGB map at 30 m resolution was generated by applying the regression model to the Landsat composite. The fivefold cross-validation with field measurements had a mean absolute error (MAE) of 25.7 Mg ha−1 (relative MAE 47.5%) and a mean bias error (MBE) of 4.3 Mg ha−1(relative MBE 7.9%). The boreal forest AGB product was compared with lidar-based vegetation height data; the comparison indicated that there was a significant correlation between the two data sets.

  17. Women and Minorities in Alaskan Aviation. Alaskan Equity Publication.

    ERIC Educational Resources Information Center

    Dordan, Mary Lou; Nicholson, Deborah

    This resource guide tells the story of Alaskan women and minority aviators and those in aviation-related businesses, from the early 20th century to the present. Developed for secondary students but also suitable for younger students, the guide combines six accounts of Alaskan women and minority aviators with classroom activities centered around…

  18. Structural and kinematic evolution of the Yukon-Tanana upland tectonites, east-central Alaska: A record of late Paleozoic to Mesozoic crustal assembly

    USGS Publications Warehouse

    Hansen, V.L.; Dusel-Bacon, C.

    1998-01-01

    The Yukon-Tanana terrane, the largest tectonostratigraphic terrane in the northern North American Cordillera, is polygenetic and not a single terrane. Lineated and foliated (L-S) tectonites, which characterize the Yukon-Tanana terrane, record multiple deformations and formed at different times. We document the polyphase history recorded by L-S tectonites within the Yukon-Tanana upland, east-central Alaska. These upland tectonites compose a heterogeneous assemblage of deformed igneous and metamorphic rocks that form the Alaskan part of what has been called the Yukon-Tanana composite terrane. We build on previous kinematic data and establish the three-dimensional architecture of the upland tectonites through kinematic and structural analysis of more than 250 oriented samples, including quartz c-axis fabric analysis of 39 samples. Through this study we distinguish allochthonous tectonites from parautochthonous tectonites within the Yukon-Tanana upland. The upland tectonites define a regionally coherent stacking order: from bottom to top, they are lower plate North American parautochthonous attenuated continental margin; continentally derived marginal-basin strata; and upper plate ocean-basin and island-arc rocks, including some continental basement rocks. We delineate three major deformation events in time, space, and structural level across the upland from the United States-Canada border to Fairbanks, Alaska: (1) pre-Early Jurassic (>212 Ma) northeast-directed, apparent margin-normal contraction that affected oceanic rocks; (2) late Early to early Middle Jurassic (>188-185 Ma) northwest-directed, apparent margin-parallel contraction and imbrication that resulted in juxtaposition of the allochthonous tectonites with parautochthonous continental rocks; and (3) Early Cretaceous (135-110 Ma) southeast-directed crustal extension that resulted in exposure of the structurally deepest, parautochthonous continental rocks. The oldest event represents deformation within a west

  19. Two flysch belts having distinctly different provenance suggest no stratigraphic link between the Wrangellia composite terrane and the paleo-Alaskan margin

    USGS Publications Warehouse

    Hults, Chad P.; Wilson, Frederic H.; Donelick, Raymond A.; O'Sullivan, Paul B.

    2013-01-01

    The provenance of Jurassic to Cretaceous flysch along the northern boundary of the allochthonous Wrangellia composite terrane, exposed from the Lake Clark region of southwest Alaska to the Nutzotin Mountains in eastern Alaska, suggests that the flysch can be divided into two belts having different sources. On the north, the Kahiltna flysch and Kuskokwim Group overlie and were derived from the Farwell and Yukon-Tanana terranes, as well as smaller related terranes that were part of the paleo-Alaskan margin. Paleocurrent indicators for these two units suggest that they derived sediment from the north and west. Sandstones are predominantly lithic wacke that contain abundant quartz grains, lithic rock fragments, and detrital mica, which suggest that these rocks were derived from recycled orogen and arc sources. Conglomerates contain limestone clasts that have fossils matching terranes that made up the paleo-Alaskan margin. In contrast, flysch units on the south overlie and were derived from the Wrangellia composite terrane. Paleocurrent indicators for these units suggest that they derived sediment from the south. Sandstones are predominantly feldspathic wackes that contain abundant plagioclase grains and volcanic rock fragments, which suggest these rocks were derived from an arc. Clast compositions in conglomerate south of the boundary match rock types of the Wrangellia composite terrane. The distributions of detrital zircon ages also differentiate the flysch units. Flysch units on the north average 54% Mesozoic, 14% Paleozoic, and 32% Precambrian detrital zircons, reflecting derivation from the older Yukon-Tanana, Farewell, and other terranes that made up the paleo-Alaskan margin. In comparison, flysch units on the south average 94% Mesozoic, 1% Paleozoic, and 5% Precambrian zircons, which are consistent with derivation from the Mesozoic oceanic magmatic arc rocks in the Wrangellia composite terrane. In particular, the flysch units on the south contain a large

  20. Fire, Carbon, and Greenhouse Gas Emissions from Aquatic Ecosystems in the Yukon-Kuskokwim River Delta

    NASA Astrophysics Data System (ADS)

    Schade, J. D.; Kuhn, M. A.; Mann, P. J.; Holmes, R. M.; Natali, S.; Ludwig, S.; Wagner, S.

    2016-12-01

    Northern latitudes are experiencing rapid changes in climate that are profoundly altering permafrost-dominated ecosystems. Increased permafrost thaw and fire frequency and severity are changing the structure and function of these ecosystems in ways likely to alter greenhouse gas (GHG) emission, leading to feedbacks on climate that may accelerate warming. Our objective was to investigate changes in GHG emissions and carbon and nitrogen dynamics in aquatic ecosystems in response to recent fires in the Yukon-Kuskokwim river delta in western Alaska. In summer 2015, more area in the YK Delta burned then in the previous 74 years combined (726 km2 in 2015 vs. 477 km2 during 1940-2014). In June of 2016, we sampled water and dissolved gases from a variety of aquatic ecosystems, including small upland ponds and wetlands and streams lower in the landscape, in recently burned and control sites near the Kuka Creek 2015 burn scar in the Yukon Delta National Wildlife Refuge. We measured a range of physical parameters, including water temperature, conductivity, dissolved oxygen, and pH. We also estimated fluxes of CO2 and CH4 from surface waters using a floating chamber connected to a Los Gatos Ultraportable gas analyzer. Water samples were analyzed for dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). Results show reduced DOC concentrations in small upland ponds in burned sites and evidence for loss of DOC downslope in control sites. In contrast, TDN concentration was higher in streams draining burned sites, suggesting fire mobilized N in soils, which was then transported to downslope ecosystems. Furthermore, fire generally increased pH, particularly in small ponds. Finally, we observed 3-4 fold higher CO2 and CH4 fluxes from aquatic ecosystems in burned sites as compared with control sites. We hypothesize that this is due to increased thaw depth and increased pH, which combine to increase resource availability and release methane-producing microbes from the

  1. Alaskan Natives and Other Minorities in the Special Education Programs of Four Alaskan School Districts.

    ERIC Educational Resources Information Center

    Pilla, Thomas V.

    This report provides information on the percentages of Native Alaskans and other minorities in the special education programs of four Alaskan school districts. It was prompted by a civil rights complaint by parents in the Juneau School District alleging that Native Alaskans were overrepresented in special education programs. The complaint was…

  2. Influence of permafrost distribution on groundwater flow in the context of climate-driven permafrost thaw: example from Yukon Flats Basin, Alaska, United States

    USGS Publications Warehouse

    Walvoord, Michelle Ann; Voss, Clifford I.; Wellman, Tristan P.

    2012-01-01

    Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km2) subbasin within the Yukon River Basin, provides the basis for this investigation. Model simulations that represent an assumed permafrost thaw sequence reveal the following trends with decreasing permafrost coverage: (1) increased groundwater discharge to rivers, consistent with historical trends in base flow observations in the Yukon River Basin, (2) potential for increased overall groundwater flux, (3) increased spatial extent of groundwater discharge in lowlands, and (4) decreased proportion of suprapermafrost (shallow) groundwater contribution to total base flow. These trends directly affect the chemical composition and residence time of riverine exports, the state of groundwater-influenced lakes and wetlands, seasonal river-ice thickness, and stream temperatures. Presently, the YFB is coarsely mapped as spanning the continuous-discontinuous permafrost transition that model analysis shows to be a critical threshold; thus, the YFB may be on the verge of major hydrologic change should the current permafrost extent decrease. This possibility underscores the need for improved characterization of permafrost and other hydrogeologic information in the region via geophysical techniques, remote sensing, and ground-based observations.

  3. Tundra ponds of the Yukon Delta, Alaska, and their macroinvertebrate communities.

    USGS Publications Warehouse

    Maciolek, J.A.

    1989-01-01

    The Yukon Delta, a low alluvial tundra in western Alaska, has more than 105 thaw-basin ponds within its 70000 km2 area. In 1984 and 1985, 68 ponds in three interior areas of the Delta were surveyed to determine limnological features, macroinvertebrate fauna, and trophic character. Ponds ranged up to 90 ha in area, 2 m in depth, and 17 m in elevation, and occurred in various temporal stages of growth and senescence. Among the 18 major invertebrate taxa collected, in order of decreasing frequency of occurrence, Trichoptera, Hemiptera, Diptera, Pelecypoda, Isopoda, Coleoptera, Gastropoda, and Oligochaeta were found in over 50% of the ponds. Trichoptera, the only taxon occurring in all ponds, was represented by 22 species of 6 families. The average Delta pond had 6.6 of the nine more common taxa. This measure of faunal richness was similar among study areas but was higher in low-tundra (sea level) ponds and in older ponds on raised tundra. In comparison, lentic invertebrate communities in five other areas of Alaskan and Canadian tundra had fewer taxa and also lower average richness based on occurrence of the same nine taxa.

  4. Novel insights from NMR spectroscopy into seasonal changes in the composition of dissolved organic matter exported to the Bering Sea by the Yukon River

    NASA Astrophysics Data System (ADS)

    Cao, Xiaoyan; Aiken, George R.; Spencer, Robert G. M.; Butler, Kenna; Mao, Jingdong; Schmidt-Rohr, Klaus

    2016-05-01

    Seasonal (spring freshet, summer-autumn, and winter) variability in the chemical composition of dissolved organic matter (DOM) from the Yukon River was determined using advanced one- and two-dimensional (2D) solid-state NMR spectroscopy, coupled with isotopic measurements and UV-visible spectroscopy. Analyses were performed on two major DOM fractions, the hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions obtained using XAD resins. Together these two fractions comprised 64-74% of the total DOM. Carboxyl-rich alicyclic molecules (CRAM) accounted for the majority of carbon atoms in the HPOA (63-77%) and TPIA (54-78%) samples, and more so in winter and summer than in spring samples. 2D and selective NMR data revealed association of abundant nonprotonated O-alkyl and quaternary alkyl C (OCnp, OCnpO and Cq, 13-17% of HPOA and 15-20% of TPIA) and isolated O-CH structures with CRAM, which were not recognized in previous studies. Spectral editing and 2D NMR allowed for the discrimination of carbohydrate-like O-alkyl C from non-carbohydrate O-alkyl C. Whereas two spring freshet TPIA samples contained carbohydrate clusters such as carboxylated carbohydrates (16% and 26%), TPIA samples from other seasons or HPOA samples mostly had small amounts (<8%) of sugar rings dispersed in a nonpolar alkyl environment. Though nonprotonated aromatic C represented the largest fraction of aromatic C in all HPOA/TPIA isolates, only a small fraction (∼5% in HPOA and 3% in TPIA) was possibly associated with dissolved black carbon. Our results imply a relatively stable portion of DOM exported by the Yukon River across different seasons, due to the predominance of CRAM and their associated nonprotonated C-O and O-C-O structures, and elevated reactivity (bio- and photo-lability) of spring DOM due to the presence of terrestrial inputs enriched in carbohydrates and aromatic structures.

  5. Estimation of selected flow and water-quality characteristics of Alaskan streams

    USGS Publications Warehouse

    Parks, Bruce; Madison, R.J.

    1985-01-01

    Although hydrologic data are either sparse or nonexistent for large areas of Alaska, the drainage area, area of lakes, glacier and forest cover, and average precipitation in a hydrologic basin of interest can be measured or estimated from existing maps. Application of multiple linear regression techniques indicates that statistically significant correlations exist between properties of basins determined from maps and measured streamflow characteristics. This suggests that corresponding characteristics of ungaged basins can be estimated. Streamflow frequency characteristics can be estimated from regional equations developed for southeast, south-central and Yukon regions. Statewide or modified regional equations must be used, however, for the southwest, northwest, and Arctic Slope regions where there is a paucity of data. Equations developed from basin characteristics are given to estimate suspended-sediment values for glacial streams and, with less reliability, for nonglacial streams. Equations developed from available specific conductance data are given to estimate concentrations of major dissolved inorganic constituents. Suggestions are made for expanding the existing data base and thus improving the ability to estimate hydrologic characteristics for Alaskan streams. (USGS)

  6. Impacts of precipitation seasonality and ecosystem types on evapotranspiration in the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Yuan, W.; Liu, S.; Liu, H.; Randerson, J.T.; Yu, G.; Tieszen, L.L.

    2010-01-01

    Evapotranspiration (ET) is the largest component of water loss from terrestrial ecosystems; however, large uncertainties exist when estimating the temporal and spatial variations of ET because of concurrent shifts in the magnitude and seasonal distribution of precipitation as well as differences in the response of ecosystem ET to environmental variabilities. In this study, we examined the impacts of precipitation seasonality and ecosystem types on ET quantified by eddy covariance towers from 2002 to 2004 in three ecosystems (grassland, deciduous broadleaf forest, and evergreen needleleaf forest) in the Yukon River Basin, Alaska. The annual precipitation changed greatly in both magnitude and seasonal distribution through the three investigated years. Observations and model results showed that ET was more sensitive to precipitation scarcity in the early growing season than in the late growing season, which was the direct result of different responses of ET components to precipitation in different seasons. The results demonstrated the importance of seasonal variations of precipitation in regulating annual ET and overshadowing the function of annual precipitation. Comparison of ET among ecosystems over the growing season indicated that ET was largest in deciduous broadleaf, intermediate in evergreen needleleaf, and lowest in the grassland ecosystem. These ecosystem differences in ET were related to differences in successional stages and physiological responses.

  7. Effect of Ichthyophonus on blood plasma chemistry of spawning Chinook salmon and their resulting offspring in a Yukon River tributary.

    PubMed

    Floyd-Rump, T P; Horstmann-Dehn, L A; Atkinson, S; Skaugstad, C

    2017-01-24

    Ichthyophonus is a protozoan parasite of Alaska Chinook salmon Oncorhynchus tshawytscha. In this study, we determined whether spawning Chinook salmon in the Yukon River drainage exhibited a measurable stress response (i.e. elevated plasma cortisol concentrations) and detectable changes in selected blood plasma chemistry parameters when infected with Ichthyophonus. The resulting alevin were also analyzed for any differences in blood plasma chemistry caused by parental infection with Ichthyophonus. In 2010, 2011, and 2012, spawning adult Chinook salmon were collected from the Salcha River, Alaska, USA, and the prevalence of Ichthyophonus in these fish was 7.8, 6.3, and 8.3%, respectively. Fish with no clinical signs of Ichthyophonus and Ichthyophonus-positive parents were cross-fertilized to investigate potential second-generation effects as a result of Ichthyophonus infection. We found no significant difference in cortisol concentrations in blood plasma between Ichthyophonus-positive and -negative adults or between alevin from Ichthyophonus-positive and -negative parents. There were no significant differences in blood plasma parameters (e.g. alanine aminotransferase, creatine kinase, glucose) of Ichthyophonus-negative and -positive adults, with the exception of aspartate aminotransferase, which was significantly higher in plasma of Ichthyophonus-negative adults. All clinical chemistry parameters for alevin resulting from both Ichthyophonus-negative and -positive parents were not significantly different. Based on this study, which has a limited sample size and low prevalence of Ichthyophonus, offspring of Chinook salmon appear to suffer no disadvantage as a result of Ichthyophonus infection in their parents on the Salcha River.

  8. Reconnaissance sedimentology of selected tertiary exposures in the upland region bordering the Yukon Flats basin, east-central Alaska

    USGS Publications Warehouse

    LePain, David L.; Stanley, Richard G.

    2017-01-01

    This report summarizes reconnaissance sedimentologic and stratigraphic observations made during six days of helicopter-supported fieldwork in 2002 on Tertiary sedimentary rocks exposed in the upland region around the flanks of the Yukon Flats basin in east-central Alaska (fig. 1). This project was a cooperative effort between the Alaska Division of Geological & Geophysical Surveys (DGGS) and the U.S. Geological Survey (USGS) to investigate the geology of the basin in preparation for an assessment of the undiscovered, technically recoverable hydrocarbon resources (Stanley and others, 2004). Field observations and interpretations summarized in this report are reconnaissance level. At most, no more than a few hours were spent on the ground at any location. Measured sections included in this report are sketch sec- tions and thicknesses shown are approximate. Relatively detailed observations were made by the authors at only three locations, including The Mudbank (Hodzana River), Rampart (east bank of the Yukon River), and Bryant Creek (along the Tintina fault near the Canada border). These three locations are described first in relative detail, then followed by general descriptions of other locations.

  9. Effects of disturbance and climate change on ecosystem performance in the Yukon River Basin boreal forest

    USGS Publications Warehouse

    Wylie, Bruce K.; Rigge, Matthew B.; Brisco, Brian; Mrnaghan, Kevin; Rover, Jennifer R.; Long, Jordan

    2014-01-01

    A warming climate influences boreal forest productivity, dynamics, and disturbance regimes. We used ecosystem models and 250 m satellite Normalized Difference Vegetation Index (NDVI) data averaged over the growing season (GSN) to model current, and estimate future, ecosystem performance. We modeled Expected Ecosystem Performance (EEP), or anticipated productivity, in undisturbed stands over the 2000–2008 period from a variety of abiotic data sources, using a rule-based piecewise regression tree. The EEP model was applied to a future climate ensemble A1B projection to quantify expected changes to mature boreal forest performance. Ecosystem Performance Anomalies (EPA), were identified as the residuals of the EEP and GSN relationship and represent performance departures from expected performance conditions. These performance data were used to monitor successional events following fire. Results suggested that maximum EPA occurs 30–40 years following fire, and deciduous stands generally have higher EPA than coniferous stands. Mean undisturbed EEP is projected to increase 5.6% by 2040 and 8.7% by 2070, suggesting an increased deciduous component in boreal forests. Our results contribute to the understanding of boreal forest successional dynamics and its response to climate change. This information enables informed decisions to prepare for, and adapt to, climate change in the Yukon River Basin forest.

  10. Dissolved organic matter composition of winter flow in the Yukon River basin: Implications of permafrost thaw and increased groundwater discharge

    USGS Publications Warehouse

    O'Donnell, Jonathan A.; Aiken, George R.; Walvoord, Michelle Ann; Butler, Kenna D.

    2012-01-01

    Groundwater discharge to rivers has increased in recent decades across the circumpolar region and has been attributed to thawing permafrost in arctic and subarctic watersheds. Permafrost-driven changes in groundwater discharge will alter the flux of dissolved organic carbon (DOC) in rivers, yet little is known about the chemical composition and reactivity of dissolved organic matter (DOM) of groundwater in permafrost settings. Here, we characterize DOM composition of winter flow in 60 rivers and streams of the Yukon River basin to evaluate the biogeochemical consequences of enhanced groundwater discharge associated with permafrost thaw. DOC concentration of winter flow averaged 3.9 ± 0.5 mg C L−1, yet was highly variable across basins (ranging from 20 mg C L−1). In comparison to the summer-autumn period, DOM composition of winter flow had lower aromaticity (as indicated by specific ultraviolet absorbance at 254 nm, or SUVA254), lower hydrophobic acid content, and a higher proportion of hydrophilic compounds (HPI). Fluorescence spectroscopy and parallel factor analysis indicated enrichment of protein-like fluorophores in some, but not all, winter flow samples. The ratio of DOC to dissolved organic nitrogen, an indicator of DOM biodegradability, was positively correlated with SUVA254 and negatively correlated with the percentage of protein-like compounds. Using a simple two-pool mixing model, we evaluate possible changes in DOM during the summer-autumn period across a range of conditions reflecting possible increases in groundwater discharge. Across three watersheds, we consistently observed decreases in DOC concentration and SUVA254 and increases in HPI with increasing groundwater discharge. Spatial patterns in DOM composition of winter flow appear to reflect differences in the relative contributions of groundwater from suprapermafrost and subpermafrost aquifers across watersheds. Our findings call for more explicit consideration of DOC loss and stabilization

  11. Tephrochronolgical Studies of Late Neogene Sediments in Interior Alaska and the Yukon Territory

    NASA Astrophysics Data System (ADS)

    Westgate, J. A.; Preece, S. J.; Froese, D. G.; Schweger, C. E.

    2004-12-01

    Our tephra studies of Late Neogene sediments in interior Alaska and Yukon are motivated by the need to provide a reliable time-stratigraphic framework for on-going palaeoenvironmental projects. Key sites are located in the Fairbanks, Chicken (Alaska) and Klondike (Yukon) goldfields, Old Crow Basin (Yukon), and the numerous bluffs along the Yukon River in Canada and eastern Alaska. Tephra beds are characterized by their field setting, petrography, geochemical composition of glass (majors and traces) and mineral phases (especially FeTi oxides), palaeomagnetic properties, and age (determined mostly by glass-fission-track methods). Two compositional groups are recognized. Type I beds have abundant bubble-wall glass shards and a small crop of crystals with pyroxene > hornblende. Its glass has a rhyolitic to dacitic composition with relatively high FeOt, Cs, Hf and low Al2O3, CaO, and Sr. REE profiles have a well-developed Eu anomaly with La/Yb < 13. Volcanics with this chemical signature are common throughout the Aleutian Alaska Peninsula arc (AAPA), which is, therefore, the presumed source of the type I distal beds. In contrast, type II beds have more abundant crystals (hornblende > > pyroxene) and the rhyolitic glass is mainly in the form of highly inflated pumice with high Al2O3, CaO, and Sr. REE profiles are steep with low heavy REE content along with a very weakly developed Eu anomaly, if present. The type II beds are unusual and have many of the characteristics of adakites, known to occur at Mount Drum and Mount Churchill in the Wrangell volcanic field (WVF), and at Hayes volcano at the northeastern end of the Alaska Peninsula arc. It is likely, therefore, that the source vents for the type II beds in interior Alaska and Yukon are located in or near the WVF. Twenty-five distinctive tephra beds have been recognized in the Gold Hill Loess at Fairbanks and a comparable number have been discovered in the Klondike goldfields, although few beds are common to both

  12. Novel insights from NMR spectroscopy into seasonal changes in the composition of dissolved organic matter exported to the Bering Sea by the Yukon River

    USGS Publications Warehouse

    Cao, Xiaoyan; Aiken, George R.; Spencer, Robert G. M.; Butler, Kenna D.; Mao, Jingdong; Schmidt-Rohr, Klaus

    2016-01-01

    Seasonal (spring freshet, summer–autumn, and winter) variability in the chemical composition of dissolved organic matter (DOM) from the Yukon River was determined using advanced one- and two-dimensional (2D) solid-state NMR spectroscopy, coupled with isotopic measurements and UV–visible spectroscopy. Analyses were performed on two major DOM fractions, the hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions obtained using XAD resins. Together these two fractions comprised 64–74% of the total DOM. Carboxyl-rich alicyclic molecules (CRAM) accounted for the majority of carbon atoms in the HPOA (63–77%) and TPIA (54–78%) samples, and more so in winter and summer than in spring samples. 2D and selective NMR data revealed association of abundant nonprotonated O-alkyl and quaternary alkyl C (OCnp, OCnpO and Cq, 13–17% of HPOA and 15–20% of TPIA) and isolated O–CH structures with CRAM, which were not recognized in previous studies. Spectral editing and 2D NMR allowed for the discrimination of carbohydrate-like O-alkyl C from non-carbohydrate O-alkyl C. Whereas two spring freshet TPIA samples contained carbohydrate clusters such as carboxylated carbohydrates (16% and 26%), TPIA samples from other seasons or HPOA samples mostly had small amounts (<8%) of sugar rings dispersed in a nonpolar alkyl environment. Though nonprotonated aromatic C represented the largest fraction of aromatic C in all HPOA/TPIA isolates, only a small fraction (∼5% in HPOA and 3% in TPIA) was possibly associated with dissolved black carbon. Our results imply a relatively stable portion of DOM exported by the Yukon River across different seasons, due to the predominance of CRAM and their associated nonprotonated C–O and O–C–O structures, and elevated reactivity (bio- and photo-lability) of spring DOM due to the presence of terrestrial inputs enriched in carbohydrates and aromatic structures.

  13. Remote and Unresearched: Educational Leadership in Canada's Yukon Territory

    ERIC Educational Resources Information Center

    Blakesley, Simon

    2008-01-01

    Educational leadership is a field that historically has not been closely examined in the Yukon Territory. The generation of Yukon-specific theory therefore remains difficult, particularly given the historical absence of an Indigenous cultural lens through which to examine educational leadership. This is the central argument presented by this…

  14. Cardiovascular Deaths among Alaskan Natives, 1980-86.

    ERIC Educational Resources Information Center

    Middaugh, John P.

    1990-01-01

    Analyzes death certificate data to discover the number of deaths of Alaskan natives caused by cardiovascular disease. Rates from cardiovascular diseases and atherosclerosis from 1980-86 among Alaskan natives were lower than rates among other Alaskans, while death rates from other causes were higher. Discusses the possible impact of diet. (JS)

  15. Summary of reconnaissance for radioactive deposits in Alaska, 1945-1954, and an appraisal of Alaskan uranium possibilities

    USGS Publications Warehouse

    Wedow, Helmuth

    1956-01-01

    carnotite-type deposits. The chief of these areas is the Alaska Peninsula-Cook Inlet area which encompasses most of the reported occurrences of the prospectors' carnotite-type samples. Alaska is also potentially favorable for the occurrence of large bodies of the very low-grade uraniferous sedimentary rocks, such as phosphorites and black shales. This type of deposit, however, has not received much study because of the emphasis on the search for bonanza-type high-grade ores. Uraniferous phosphorites similar to those of Idaho, Montana, and Wyoming occur in northern Alaska on the north flank of the Brooks Range; black shales comparable to the uraniferous shales of the Chattanooga formation of southeastern United States have been noted along the Yukon River near the international boundary. Placer deposits in Alaska have some small potential for the production of the radioactive elements as byproducts of gold- and tin-placer mining. the placer area believed to have the relatively greatest potential in Alaska lies in the Kahiltna River valley where concentrates are known to contain such commercial minerals as ilmenite, cassiterite, platinum, and gold in addition to uranothorianite and monazite. The possibilities of the natural fluids--water and petroleum--have not yet been tested in Alaska to any great extent. Studies of fluids are in progress to determine whether they may be used to discover and define areas potentially favorable for the occurrence of uraniferous lodes.

  16. Impact-related microspherules in Late Pleistocene Alaskan and Yukon “muck” deposits signify recurrent episodes of catastrophic emplacement

    USGS Publications Warehouse

    Hagstrum, Jonathan T.; Firestone, Richard B.; West, Allen; Weaver, James C.; Bunch, Ted E.

    2017-01-01

    Large quantities of impact-related microspherules have been found in fine-grained sediments retained within seven out of nine, radiocarbon-dated, Late Pleistocene mammoth (Mammuthus primigenius) and bison (Bison priscus) skull fragments. The well-preserved fossils were recovered from frozen “muck” deposits (organic-rich silt) exposed within the Fairbanks and Klondike mining districts of Alaska, USA, and the Yukon Territory, Canada. In addition, elevated platinum abundances were found in sediment analysed from three out of four fossil skulls. In view of this new evidence, the mucks and their well-preserved but highly disrupted and damaged vertebrate and botanical remains are reinterpreted in part as blast deposits that resulted from several episodes of airbursts and ground/ice impacts within the northern hemisphere during Late Pleistocene time (~46–11 ka B.P.). Such a scenario might be explained by encounters with cometary debris in Earth-crossing orbits (Taurid Complex) that was generated by fragmentation of a large short-period comet within the inner Solar System.

  17. 75 FR 11905 - Yukon Flats National Wildlife Refuge, Fairbanks, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-12

    ... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R7-R-2009-N282; 70133-1265-0000-U4] Yukon Flats National Wildlife Refuge, Fairbanks, AK AGENCY: U.S. Fish and Wildlife Service, Interior. ACTION: Notice of availability of proposed land exchange Yukon Flats National Wildlife Refuge final...

  18. Mapping Soil Carbon in the Yukon Kuskokwim River Delta Alaska

    NASA Astrophysics Data System (ADS)

    Natali, S.; Fiske, G.; Schade, J. D.; Mann, P. J.; Holmes, R. M.; Ludwig, S.; Melton, S.; Sae-lim, N.; Jardine, L. E.; Navarro-Perez, E.

    2017-12-01

    Arctic river deltas are hotspots for carbon storage, occupying <1% of the pan-Arctic watershed but containing >10% of carbon stored in arctic permafrost. The Yukon Kuskokwim (YK) Delta, Alaska is located in the lower latitudinal range of the northern permafrost region in an area of relatively warm permafrost that is particularly vulnerable to warming climate. Active layer depths range from 50 cm on peat plateaus to >100 cm in wetland and aquatic ecosystems. The size of the soil organic carbon pool and vulnerability of the carbon in the YK Delta is a major unknown and is critically important as climate warming and increasing fire frequency may make this carbon vulnerable to transport to aquatic and marine systems and the atmosphere. To characterize the size and distribution of soil carbon pools in the YK Delta, we mapped the land cover of a 1910 km2 watershed located in a region of the YK Delta that was impacted by fire in 2015. The map product was the result of an unsupervised classification using the Weka K Means clustering algorithm implemented in Google's Earth Engine. Inputs to the classification were Worldview2 resolution optical imagery (1m), Arctic DEM (5m), and Sentinel 2 level 1C multispectral imagery, including NDVI, (10 m). We collected 100 soil cores (0-30 cm) from sites of different land cover and landscape position, including moist and dry peat plateaus, high and low intensity burned plateaus, fens, and drained lakes; 13 lake sediment cores (0-50 cm); and 20 surface permafrost cores (to 100 cm) from burned and unburned peat plateaus. Active layer and permafrost soils were analyzed for organic matter content, soil moisture content, and carbon and nitrogen pools (30 and 100 cm). Soil carbon content varied across the landscape; average carbon content values for lake sediments were 12% (5- 17% range), fens 26% (9-44%), unburned peat plateaus 41% (34-44%), burned peat plateaus 19% (7-34%). These values will be used to estimate soil carbon pools, which will

  19. Effects of Fire on Understory Vegetation Communities in Siberian Boreal Forests and Alaskan Tundra

    NASA Astrophysics Data System (ADS)

    Pena, H., III; Alexander, H. D.; Natali, S.; Loranty, M. M.; Holmes, R. M.; Mack, M. C.; Schade, J. D.; Mann, P. J.; Davydov, S. P.; Frey, B.; Zimov, N.; Jardine, L. E.

    2017-12-01

    Fire is an important disturbance in Arctic ecosystems that is increasing in frequency and severity as a result of climate warming. Fire alters the landscape, changes soil conditions, and influences vegetation regrowth, favoring early-successional plants and those with well-established root systems capable of surviving fire. Post-fire vegetation establishment contributes to the recovery of the soil organic layer (SOL), which insulates the soil and protects soil and permafrost carbon pools. In order to better understand successional dynamics following fire in the Arctic we assessed the short-(years) and long-(decades) term effects of fire on vegetation communities, SOL depth, and thaw depth across fire-affected sites located in two regions of the Arctic- a 76-year old fire scar in a larch forest in Siberia near Cherskiy, Russia, and a 2-year old fire scar in tundra in the Yukon-Kuskokwim Delta, Alaska. We measured species diversity, plant carbon (C) pools, SOL conditions and NDVI at both study areas. As expected, there was a decline in vegetation C pools following fire in Alaskan tundra, and as a result of higher severity fire in Siberian boreal forests. Two years following fire in Alaskan tundra, vegetation C pools decreased six-fold from 600 g C m-2 at unburned areas, to 100 g C m-2 at the 2015 burn areas. In larch forests, understory C pools were three-times lower in stands with high intensity fires (135 g C m-2) compared to those with low intensity fires (415 g C m-2), due to the absence of dwarf birch (Betula nana). Our results illustrate how fire influences vegetation at both early and later stages of succession, which can have cascading effects on SOL development and permafrost integrity, with the potential for release of large C stocks that may further exacerbate climate warming.

  20. Nesting ecology of tundra swans on the coastal Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Babcock, C.A.; Fowler, A.C.; Ely, Craig R.

    2002-01-01

    Nesting ecology of Tundra Swans (Cygnus columbianus columbianus) was studies the Kashunuk River near Old Chevak (61A?26a??N, 165A?27a??W), on the Yukon-Kuskokwim Delta of western Alaska from 1988-2000. Annual variation in snow-melt chronology, nesting phenology, nesting density, clutch size and nest success was examined. The same area (approximately 23 kmA?) was searched each year and nests were found as early as possible in the laying period. Laying initiation dates ranged from 1-27 May and hatch dates from 12 June a?? 4 July among pairs and years of study. The peak arrival of Tundra Swans and the phenology of nest initiation and hatch were highly correlated with the progression of ice and snow melt in spring. Nest density averaged 0.71 kmA? and 89% of nesting pairs hatched at least one egg. Incubation period ranged from 26 to 33 days with a median of 30 days. Clutch size varied significantly among years, driven by a low mean value of 3.4 eggs in 1999. Clutch sizes were generally larger than found in previous investigations on the Yukon-Kuskokwim Delta, and nearly one egg larger than reported for clutches from Alaskaa??s North Slope (=70A?N). There was no indication of reduced clutch size in years of late spring snow melt, although nesting density tended to be lower.

  1. Temperature sensitivity of DOC production and transformation in organic soils of the Yukon River Basin, Alaska

    NASA Astrophysics Data System (ADS)

    O'Donnell, J.; Butler, K. D.; Aiken, G.

    2012-12-01

    The flux of dissolved organic carbon (DOC) from terrestrial to aquatic ecosystems represents a critical component of the high-latitude carbon balance. In the Yukon River basin (YRB), DOC fluxes have declined in recent decades, likely in response to regional permafrost thaw and increased groundwater discharge to river flow. Despite improved flux estimates for many arctic rivers, considerable uncertainty exists regarding the potential response of DOC fluxes to projected warming. To improve estimates of future DOC dynamics, it is important to develop a process-based approach whereby empirical constraints are placed on source and sink terms in both soil and river systems. Here, we examine variability in DOC production and microbially mediated transformations as a function of both temperature and organic matter (OM) composition in soils of the YRB. We conducted "tea" experiments by incubating three organic-soil types that vary with depth and decomposition extent (live/dead moss, fibric OM and humic OM) at two temperatures (4 vs. 20 °C). Leachate samples were collected periodically over a 30-day incubation and characterized for DOC concentration, optical properties (specific UV absorbance at 254 nm or SUVA254, fluorescence), and major chemical fractions using XAD8/XAD4 resins. We observed a non-linear increase in DOC production over time, characterized by a rapid initial release of DOC from soils followed by a slower rise in DOC concentration in subsequent weeks. Mean DOC concentration was described by a significant interaction between organic-soil type and temperature, indicating a strong relationship between temperature sensitivity of net DOC production and the decomposition extent of soil OM. On average across all sampling dates, DOC concentrations were highest in leachate from fibric OM (13.4 to 17.8 mgC L-1), and lowest in leachate from humic OM (3.5 to 8.5 mgC L-1). However, the temperature sensitivity of net DOC production was highest in the humic OM treatment

  2. Isoscapes of δ18O and δ2H reveal climatic forcings on Alaska and Yukon precipitation

    NASA Astrophysics Data System (ADS)

    Lachniet, Matthew S.; Lawson, Daniel E.; Stephen, Haroon; Sloat, Alison R.; Patterson, William P.

    2016-08-01

    Spatially extensive Arctic stable isotope data are sparse, inhibiting the climatic understanding required to interpret paleoclimate proxy records. To fill this need, we constrained the climatic and physiographic controls on δ18O and δD values of stream waters across Alaska and the Yukon to derive interpolated isoscape maps. δ18O is strongly correlated to winter temperature parameters and similarity of the surface water line (δ2H = 8.0 × δ18O + 6.4) to the Global Meteoric Water Line suggests stream waters are a proxy for meteoric precipitation. We observe extreme orographic δ18O decreases and a trans-Alaskan continental gradient of -8.3‰ 1000 km-1. Continental gradients are high in coastal zones and low in the interior. Localized δ18O increases indicate inland air mass penetration via topographic lows. Using observed δ18O/temperature gradients, we show that δ18O decreases in a ˜24 ka permafrost ice wedge relative to the late Holocene indicate mean annual and coldest quarter temperature reductions of 8.9 ± 1.7°C and 17.2 ± 3.2°C, respectively.

  3. River conservation and terrestrial mammals: key ecological processes

    Treesearch

    Thomas A. Hanley

    2008-01-01

    Key ecological processes affecting interactions between rivers and terrestrial mammals are identified and explained, using flood plains of Alaska as examples of relatively pristine systems. Both coastal (southeast Alaska) and interior Alaska examples are used. Coastal Alaskan rivers tend to be relatively short, flashy, rain-driven systems, whereas interior Alaska...

  4. Interdisciplinary approach to hydrological hazard mitigation and disaster response and effects of climate change on the occurrence of flood severity in central Alaska

    NASA Astrophysics Data System (ADS)

    Kontar, Y. Y.; Bhatt, U. S.; Lindsey, S. D.; Plumb, E. W.; Thoman, R. L.

    2015-06-01

    In May 2013, a massive ice jam on the Yukon River caused flooding that destroyed much of the infrastructure in the Interior Alaska village of Galena and forced the long-term evacuation of nearly 70% of its residents. This case study compares the communication efforts of the out-of-state emergency response agents with those of the Alaska River Watch program, a state-operated flood preparedness and community outreach initiative. For over 50 years, the River Watch program has been fostering long-lasting, open, and reciprocal communication with flood prone communities, as well as local emergency management and tribal officials. By taking into account cultural, ethnic, and socioeconomic features of rural Alaskan communities, the River Watch program was able to establish and maintain a sense of partnership and reliable communication patterns with communities at risk. As a result, officials and residents in these communities are open to information and guidance from the River Watch during the time of a flood, and thus are poised to take prompt actions. By informing communities of existing ice conditions and flood threats on a regular basis, the River Watch provides effective mitigation efforts in terms of ice jam flood effects reduction. Although other ice jam mitigation attempts had been made throughout US and Alaskan history, the majority proved to be futile and/or cost-ineffective. Galena, along with other rural riverine Alaskan communities, has to rely primarily on disaster response and recovery strategies to withstand the shock of disasters. Significant government funds are spent on these challenging efforts and these expenses might be reduced through an improved understanding of both the physical and climatological principals behind river ice breakup and risk mitigation. This study finds that long term dialogue is critical for effective disaster response and recovery during extreme hydrological events connected to changing climate, timing of river ice breakup, and

  5. Geomorphic controls on floodplain organic carbon storage in sediment along five rivers in interior Alaska

    NASA Astrophysics Data System (ADS)

    Lininger, K.; Wohl, E.; Rose, J. R.

    2016-12-01

    High latitude permafrost regions contain large amounts of organic carbon (OC) in the subsurface, but little work has quantified OC storage in floodplain sediment in the high latitudes. Floodplains influence the export of OC to the ocean by temporarily storing OC at timescales of 101 to 103 years. To fully understand terrestrial carbon cycling, the storage and residence time of OC in floodplains, and the geomorphic controls on OC storage, must be taken into account. Small-scale spatial variations in OC storage within floodplains likely reflect geomorphic processes of deposition and floodplain development. We present results of floodplain OC storage and residence time in sediment along 5 rivers in the Yukon Flats National Wildlife Refuge in interior Alaska, a region with discontinuous permafrost. We collected sediment samples within the active layer along tributaries to the Yukon River and the mainstem Yukon River and analyzed the sediment samples for OC content. We classified sample locations by geomorphic type (filled secondary channels, levees, point bars) and vegetation type (herbaceous, deciduous/shrub, white spruce, and black spruce wetlands), and found that both geomorphology and vegetation influence OC concentration and OC mass per area. Preliminary results suggest that filled secondary channels contain more OC per area compared to other geomorphic types. We present results of radiocarbon dates from river cutbanks associated with our sampling sites, which give a maximum age for residence times of OC in sediment before erosion and transport. The radiocarbon dates also provide estimates of long-term OC accretion within the Yukon Flats floodplains. Small-scale variations within floodplains as a result of floodplain depositional processes and vegetation communities shed light on the geomorphic controls on OC storage. This work will help constrain the spatial variation in OC storage and OC residence time across the landscape in a region experiencing rapid climate

  6. New ichnological, paleobotanical and detrital zircon data from an unnamed rock unit in Yukon-Charley Rivers National Preserve (Cretaceous: Alaska): Stratigraphic implications for the region

    USGS Publications Warehouse

    Fiorillo, Anthony R.; Fanti, Federico; Hults, Chad; Hasiotis, Stephen T

    2014-01-01

    A paleontological reconnaissance survey on Cretaceous and Paleogene terrestrial units along the Yukon River drainage through much of east-central Alaska has provided new chronostratigraphic constraints, paleoclimatological data, and the first information on local biodiversity within an ancient, high-latitude ecosystem. The studied unnamed rock unit is most notable for its historic economic gold placer deposits, but our survey documents its relevance as a source rock for Mesozoic terrestrial vertebrates, invertebrates, and associated flora. Specifically, new U-Pb ages from detrital zircons combined with ichnological data are indicative of a Late Cretaceous age for at least the lower section of the studied rock unit, previously considered to be representative of nearly exclusively Paleogene deposition. Further, the results of our survey show that this sedimentary rock unit preserves the first record of dinosaurs in the vast east-central Alaska region. Lastly, paleobotanical data, when compared to correlative rock units, support previous interpretations that the Late Cretaceous continental ecosystem of Alaska was heterogeneous in nature and seasonal.

  7. Teaching in the Yukon: Exploring Teachers' Efficacy Beliefs, Stress, and Job Satisfaction in a Remote Setting

    ERIC Educational Resources Information Center

    Klassen, Robert M.; Foster, Rosemary Y.; Rajani, Sukaina; Bowman, Carley

    2009-01-01

    This article presents a mixed methods examination of teachers' job beliefs in the Yukon Territory in northern Canada. In Study 1 we used questionnaires to examine job beliefs for 221 teachers from the Yukon and western Canada. Teachers' self- and collective efficacy and workload stress were lower for Yukon teachers, but levels of overall stress…

  8. The Healthy Eating Handbook for Yukon First Nations. Occasional Publication No. 39.

    ERIC Educational Resources Information Center

    Nardelli, Vanessa M.; Wein, Eleanor E.

    The purpose of this handbook is to develop positive attitudes and skills toward healthy eating and healthy lifestyles among Yukon First Nations people. The introduction describes traditional food sources of the Yukon and how Native peoples met their nutritional needs by eating a variety of wild animal, fish, and plant foods. However, current…

  9. The influence of hydrology and waterway distance on population structure of Chinook salmon Oncorhynchus tshawytscha in a large river.

    PubMed

    Olsen, J B; Beacham, T D; Wetklo, M; Seeb, L W; Smith, C T; Flannery, B G; Wenburg, J K

    2010-04-01

    Adult Chinook salmon Oncorhynchus tshawytscha navigate in river systems using olfactory cues that may be influenced by hydrologic factors such as flow and the number, size and spatial distribution of tributaries. Thus, river hydrology may influence both homing success and the level of straying (gene flow), which in turn influences population structure. In this study, two methods of multivariate analysis were used to examine the extent to which four indicators of hydrology and waterway distance explained population structure of O. tshawytscha in the Yukon River. A partial Mantel test showed that the indicators of hydrology were positively associated with broad-scale (Yukon basin) population structure, when controlling for the influence of waterway distance. Multivariate multiple regression showed that waterway distance, supplemented with the number and flow of major drainage basins, explained more variation in broad-scale population structure than any single indicator. At an intermediate spatial scale, indicators of hydrology did not appear to influence population structure after accounting for waterway distance. These results suggest that habitat changes in the Yukon River, which alter hydrology, may influence the basin-wide pattern of population structure in O. tshawytscha. Further research is warranted on the role of hydrology in concert with waterway distance in influencing population structure in Pacific salmon.

  10. Observations of geese foraging for clam shells during spring on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Fowler, Ada C.; Bottitta, Grace E.; Schamber, Jason L.

    1998-01-01

    We studied the behavior of geese on exposed river ice during spring on the Yukon-Kuskokwim Delta. The predominant behavior while on the ice for both sexes was foraging; however, females foraged more than males. Visual inspection of the ice revealed no potential plant or animal food items. However, numerous small (<20 mm) clam shells (Macoma balthica) and pieces of shell were noted. It appeared that geese were foraging on empty clam shells. This potential source of calcium was available to breeding geese just prior to egg formation and geese likely stored this calcium in the form of medullary bone for use during egg formation.

  11. Alaskan Voices.

    ERIC Educational Resources Information Center

    Achatz, Mary, Ed.; Caldera, Debra, Ed.; Saylor, Brian; DeGross, Denny

    This paper examines the attitudes of adults and teenagers in 10 predominantly rural Alaskan communities toward their own health and well-being and that of children and families in their community. The communities were located across the state and ranged in size from populations of under 900 to over 50,000. The proportion of Alaska Natives in the…

  12. Hydrological role of large icings within glacierized Sub-Arctic watershed: case study in Upper Duke River valley, Yukon, Canada.

    NASA Astrophysics Data System (ADS)

    Chesnokova, Anna; Baraer, Michel

    2017-04-01

    Sub-Arctic glacierized catchments are complex hydrological systems of paramount importance for water resources management as well as for various ecosystem services. Such systems host many climate-sensitive water sources. Among those, icing is an important component as they provide substantial amount of water during the melt season. Moreover, collecting water of different origins during their formation, icings can be seen as an indicator for different water sources and water pathways that remain active during the freezing period. The present study focuses on genesis and dynamics of large icings within both proglacial field and neighboring alpine meadow in Upper Duke River valley, Yukon, in order to i) provide new insights on water sources and pathways within Sub-Arctic glacierized watersheds, and ii) to quantify contribution of icings to the total runoff of those hydrological systems. A multi-approach technique was applied to cope with the high hydrological complexity met in Sub-Arctic mountainous environments. Time series of positions of large river icings within the study area were obtained using Landsat images for the period 1980-2016. Four time-lapse cameras (TLC) were installed in the watershed targeting two proglacial fields and two alpine meadows in order to monitor icing dynamics all year long. Meteorological data was measured by an Automatic Weather Station in the main valley. In addition air temperature and relative humidity were measured at the location of each TLC. Finally, four icings along the Duke River valley, as well as 2 icings in its main tributary were sampled for stable water isotopes, solutes concentrations and total organic carbon. In addition, samples of freezing exclusion precipitates from icing surfaces were taken. Remote sensing data shows the persistence of large icing complexes in the area during last 30 years: icing within proglacial field appear with almost constant position relative to main glacier tongue on the 30 years long period

  13. AirSWOT Measurements of Water Surface Elevations and Hydraulic Gradients over the Yukon Flats, Alaska

    NASA Astrophysics Data System (ADS)

    Pitcher, L. H.; Pavelsky, T.; Smith, L. C.; Moller, D.; Altenau, E. H.; Lion, C.; Bertram, M.; Cooley, S. W.

    2017-12-01

    AirSWOT is an airborne, Ka-band synthetic aperture radar interferometer (InSAR) intended to quantify surface water fluxes by mapping water surface elevations (WSE). AirSWOT will also serve as a calibration/validation tool for the Surface Water and Ocean Topography (SWOT) satellite mission (scheduled for launch in 2021). The hydrology objectives for AirSWOT and SWOT are to measure WSE with accuracies sufficient to estimate hydrologic fluxes in lakes, wetlands and rivers. However, current understanding of the performance of these related though not identical instruments when applied to complex river-lake-wetland fluvial environments remains predominantly theoretical. We present AirSWOT data acquired 15-June-2015 over the Yukon Flats, Alaska, USA, together with in situ field surveys, to assess the accuracy of AirSWOT WSE measurements in lakes and rivers. We use these data to demonstrate that AirSWOT can be used to estimate large-scale hydraulic gradients across wetland complexes. Finally, we present key lessons learned from this AirSWOT analysis for consideration in future campaigns, including: maximizing swath overlap for spatial averaging to minimize uncertainty as well as orienting flight paths parallel to river flow directions to reduce along track aircraft drift for neighboring flight paths. We conclude that spatially dense AirSWOT measurements of river and lake WSEs can improve geospatial understanding of surface water hydrology and fluvial processes.

  14. In-situ Geotechnical Investigation of Arctic Nearshore Zone Sediments, Herschel Island, Yukon

    NASA Astrophysics Data System (ADS)

    Stark, N.; Quinn, B.; Radosavljevic, B.; Lantuit, H.

    2016-02-01

    The Arctic is currently undergoing rapid changes with regard to ice coverage, permafrost retreat and coastal erosion. In addition to hydrodynamic processes, the sediments in the Arctic nearshore zone are affected by potential variations in freeze-thaw cycles, as well as an increase of abundant suspended sediment introduced by active retrogressive thaw slumps and increased river discharge. During the YUKON14 expedition to Herschel Island, Yukon, in-situ geotechnical testing of nearshore zone sediments was conducted using a portable free fall penetrometer. The research goals were mapping of sediment types, identification of surficial sediment stratification related to recent sediment remobilization or deposition processes, and the investigation of the soil mechanical characteristics of the uppermost seabed surface in the nearshore zone. Approximately 200 sites were tested using the portable free fall penetrometer, and five different geotechnical signatures identified and grouped. Most locations were characterized by a soft sediment top layer that exhibited a noticeably lower sediment strength than the underlying sediment. The results were correlated to existing sediment grain size records and a sediment type interpretation based on side scan sonar backscatter information. Strong spatial variations in sediment type and stiffness were observed, as well as in abundance and thickness of a top layer of very soft and loose sediment. It was attempted to relate the geotechnical signature to site-specific hydrodynamic energy, morphology, and vicinity to thaw slumps. The results will contribute to a detailed investigation of Arctic coastal erosion in the region, and the investigation of the role of geotechnical parameters for Arctic coastal erosion.

  15. Decadal water quality variations at three typical basins of Mekong, Murray and Yukon

    NASA Astrophysics Data System (ADS)

    Khan, Afed U.; Jiang, Jiping; Wang, Peng

    2018-02-01

    Decadal distribution of water quality parameters is essential for surface water management. Decadal distribution analysis was conducted to assess decadal variations in water quality parameters at three typical watersheds of Murray, Mekong and Yukon. Right distribution shifts were observed for phosphorous and nitrogen parameters at the Mekong watershed monitoring sites while left shifts were noted at the Murray and Yukon monitoring sites. Nutrients pollution increases with time at the Mekong watershed while decreases at the Murray and Yukon watershed monitoring stations. The results implied that watershed located in densely populated developing area has higher risk of water quality deterioration in comparison to thinly populated developed area. The present study suggests best management practices at watershed scale to modulate water pollution.

  16. Relationships between High River Discharge, Upwelling Events, and Bowhead Whale (Balaena mysticetus) Occurrence in the Central Alaskan Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Clarke, J.; Okkonen, S. R.; Potter, R. A.

    2016-02-01

    Aerial surveys of bowhead whales have been conducted in September in the central Alaskan Beaufort Sea (144°W-150°W) for several decades. These surveys, co-managed by BOEM and NOAA, have documented bowhead whale distribution that is almost exclusively on the continental shelf, generally from <1 to 70 km from shore. Most whales observed in September are actively migrating and swimming in a westerly direction, with feeding behavior occasionally observed. In September 2014, several hundred bowhead whales were observed feeding on several occasions within a few kilometers of local barrier islands. This is an unusual situation that has been observed in September in only one other year (1997). To investigate local conditions that might be conducive to increased bowhead whale occurrence, freshwater discharge data from the Sagavanirktok and Kuparak rivers, surface wind data, and suspended sediment data obtained from MODIS satellite imagery were analyzed and compared to bowhead whale observations for September 1989-2014. Results indicate that anomalously high freshwater river discharge coupled with prior upwelling events, based on surface winds >5.4 m s-1, may combine to promote the aggregation of bowhead whale prey on the shallow shelf. When these two conditions were met, whales were sighted more frequently, were more likely to be in groups of ≥2 animals, and be closer to shore. Conversely, when either of the two conditions was not met, whales were sighted less frequently, more likely to be single animals, and be farther from shore. These results underscore annual variation during the bowhead whale fall migration and the physical oceanography processes that may be related to whale distribution and behavior.

  17. 7 CFR 1780.49 - Rural or Native Alaskan villages.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 12 2010-01-01 2010-01-01 false Rural or Native Alaskan villages. 1780.49 Section..., DEPARTMENT OF AGRICULTURE (CONTINUED) WATER AND WASTE LOANS AND GRANTS Loan and Grant Application Processing § 1780.49 Rural or Native Alaskan villages. (a) General. (1) This section contains regulations for...

  18. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are applicable...

  19. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are applicable...

  20. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are applicable...

  1. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are applicable...

  2. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are applicable...

  3. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are applicable...

  4. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are applicable...

  5. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart are...

  6. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart are...

  7. The prelaying interval of emperor geese on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Hupp, Jerry W.; Schmutz, J.A.; Ely, Craig R.

    2006-01-01

    We marked 136 female Emperor Geese (Chen canagica) in western Alaska with VHF or satellite (PTT) transmitters from 1999 to 2003 to monitor their spring arrival and nest initiation dates on the Yukon Delta, and to estimate prelaying interval lengths once at the nesting area. Ninety-two females with functional transmitters returned to the Yukon Delta in the spring after they were marked, and we located the nests of 35 of these individuals. Prelaying intervals were influenced by when snow melted in the spring and individual arrival dates on the Yukon Delta. The median prelaying interval was 15 days (range = 12-19 days) in a year when snow melted relatively late, and 11 days (range = 4-16 days) in two warmer years when snow melted earlier. In years when snow melted earlier, prelaying intervals of <12 days for 11 of 15 females suggested they initiated rapid follicle development on spring staging areas. The prelaying interval declined by approximately 0.4 days and nest initiation date increased approximately 0.5 days for each day a female delayed her arrival. Thus, females that arrived first on the Yukon Delta had prelaying intervals up to four days longer, yet they nested up to five days earlier, than females that arrived last. The proximity of spring staging areas on the Alaska Peninsula to nesting areas on the Yukon Delta may enable Emperor Geese to alter timing of follicle development depending on annual conditions, and to invest nutrients acquired from both areas in eggs during their formation. Plasticity in timing of follicle development is likely advantageous in a variable environment where melting of snow cover in the spring can vary by 2-3 weeks annually. ?? The Cooper Ornithological Society 2006.

  8. Alaskan Native Early School Leavers: A Study with Recommendations.

    ERIC Educational Resources Information Center

    Crumb, Jeanmarie

    In response to a request by the Anchorage Native Caucus and the Anchorage Native Education Coalition, this study by the Anchorage School District Community Relations Department focuses on the Alaskan Native dropout problem. The study indicates that between September 1976 and March 1981, Native Alaskans, who compose approximately 4% of the total…

  9. Keeping Alaskan Tradition Alive: Building Relationships in the Curriculum

    ERIC Educational Resources Information Center

    Hughes, Eileen; Forbes, Sue

    2005-01-01

    This article reviews varied types of relationships that were formed when a kindergarten class embarked on a study of the Native Alaskan art of carving. The public school kindergarten classroom, located in Anchorage, Alaska, drew from a community with a high population of Hispanic, African American, and Native Alaskan families with different…

  10. Effect of permafrost thaw on the dynamics of lakes recharged by ice-jam floods: case study in Yukon Flats, Alaska

    USGS Publications Warehouse

    Steve M. Jepsen,; Walvoord, Michelle Ann; Voss, Clifford I.; Rover, Jennifer R.

    2016-01-01

    Large river floods are a key water source for many lakes in fluvial periglacial settings. Where permeable sediments occur, the distribution of permafrost may play an important role in the routing of floodwaters across a floodplain. This relationship is explored for lakes in the discontinuous permafrost of Yukon Flats, interior Alaska, using an analysis that integrates satellite-derived gradients in water surface elevation, knowledge of hydrogeology, and hydrologic modeling. We observed gradients in water surface elevation between neighboring lakes ranging from 0.001 to 0.004. These high gradients, despite a ubiquitous layer of continuous shallow gravel across the flats, are consistent with limited groundwater flow across lake basins resulting from the presence of permafrost. Permafrost impedes the propagation of floodwaters in the shallow subsurface and constrains transmission to “fill-and-spill” over topographic depressions (surface sills), as we observed for the Twelvemile-Buddy Lake pair following a May 2013 ice-jam flood on the Yukon River. Model results indicate that permafrost table deepening of 1–11 m in gravel, depending on watershed geometry and subsurface properties, could shift important routing of floodwater to lakes from overland flow (fill-and-spill) to shallow groundwater flow (“fill-and-seep”). Such a shift is possible in the next several hundred years of ground surface warming, and may bring about more synchronous water level changes between neighboring lakes following large flood events. This relationship offers a potentially useful tool, well-suited to remote sensing, for identifying long-term changes in shallow groundwater flow resulting from thawing of permafrost.

  11. A Statistical Profile: Women in the Alaskan Community Colleges.

    ERIC Educational Resources Information Center

    Seppanen, Loretta J.

    Women's status as students and employees in Alaska's community colleges is greatly influenced by the unique Alaskan environment, where women make up only 47.6% of the population and where the population is on the whole very young. Women comprised 58% of all enrolled students in Alaskan community colleges in fall 1982 and received 56% of the…

  12. NASA Finds Sea Ice Driving Arctic Air Pollutants Alaskan North Slope

    NASA Image and Video Library

    2012-03-01

    JPL-led study shows bromine explosion on March 13, 2008 across the Alaskan North Slope looking south toward the Brooks Range at the horizon, which blocked the bromine from going further south into the Alaskan interior.

  13. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart are...

  14. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart are...

  15. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  16. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  17. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart are...

  18. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart are...

  19. Alaska Is Our Home--Book 3: A Natural Science Handbook for Alaskan Students.

    ERIC Educational Resources Information Center

    Bury, John; Bury, Susan

    The third book in a series of natural science handbooks for Alaskan students focuses on Alaskan plantlife. The first chapter, on trees, gives general information about trees and explains how to identify and locate trees in the three main Alaskan tree families: pine, willow, and birch. The second chapter, on plants, describes 14 kinds of edible…

  20. The importance of old growth refugia in the Yukon boreal forest to cavity-nesting owls

    Treesearch

    D. H. Mossop

    1997-01-01

    The Yukon's boreal forest is a slow-growing yet dynamic system greatly affected by wildfire. Trees of a diameter and age to accommodate cavity-nesting owls and other larger birds should be rare. An experiment was conducted by erecting just over 100 nest boxes throughout the southern Yukon to test the availability of nest holes for small owls. After 5 years an...

  1. Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon village, Porcupine river, east-central Alaska

    USGS Publications Warehouse

    Fouch, T.D.; Carter, L.D.; Kunk, Michael J.; Smith, C.A.S.; White, J.M.

    1994-01-01

    Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins. ?? 1994.

  2. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions of...

  3. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions of...

  4. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions of...

  5. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions of...

  6. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions of...

  7. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions of...

  8. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions of...

  9. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions of...

  10. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions of...

  11. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions of...

  12. 40 CFR 408.40 - Applicability; description of the non-remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-remote Alaskan crab meat processing subcategory. 408.40 Section 408.40 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Crab Meat Processing Subcategory § 408.40 Applicability; description of the non-remote Alaskan crab meat processing subcategory. The provisions of this subpart are...

  13. 40 CFR 408.40 - Applicability; description of the non-remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-remote Alaskan crab meat processing subcategory. 408.40 Section 408.40 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Crab Meat Processing Subcategory § 408.40 Applicability; description of the non-remote Alaskan crab meat processing subcategory. The provisions of this subpart are...

  14. 50 CFR 23.69 - How can I trade internationally in fur skins and fur skin products of bobcat, river otter, Canada...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... skins and fur skin products of bobcat, river otter, Canada lynx, gray wolf, and brown bear? 23.69... skins and fur skin products of bobcat, river otter, Canada lynx, gray wolf, and brown bear? (a) U.S. and...), river otter (Lontra canadensis), and Canada lynx (Lynx canadensis), and the Alaskan populations of gray...

  15. 50 CFR 23.69 - How can I trade internationally in fur skins and fur skin products of bobcat, river otter, Canada...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... skins and fur skin products of bobcat, river otter, Canada lynx, gray wolf, and brown bear? 23.69... skins and fur skin products of bobcat, river otter, Canada lynx, gray wolf, and brown bear? (a) U.S. and...), river otter (Lontra canadensis), and Canada lynx (Lynx canadensis), and the Alaskan populations of gray...

  16. 50 CFR 23.69 - How can I trade internationally in fur skins and fur skin products of bobcat, river otter, Canada...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... skins and fur skin products of bobcat, river otter, Canada lynx, gray wolf, and brown bear? 23.69... skins and fur skin products of bobcat, river otter, Canada lynx, gray wolf, and brown bear? (a) U.S. and...), river otter (Lontra canadensis), and Canada lynx (Lynx canadensis), and the Alaskan populations of gray...

  17. Offshore oil in the Alaskan Arctic

    NASA Technical Reports Server (NTRS)

    Weeks, W. F.; Weller, G.

    1984-01-01

    Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent natural gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occuur offshore beneath the shallow, ice-covered seas of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas.

  18. Degradation and Local Survival of Permafrost Through the Last Interglaciation in Interior Alaska and Yukon Territory

    NASA Astrophysics Data System (ADS)

    Reyes, A. V.; Froese, D. G.; Jensen, B. J.

    2006-12-01

    Permafrost in northern North America is warming, and recent modeling efforts have predicted the widespread disappearance of permafrost through much of the northern hemisphere over the next century. However, little is known of the impacts of past sustained warm intervals on permafrost dynamics, antiquity, and distribution due to difficulties in establishing reliable chronologies. Permafrost thus remains the last element of the Arctic cryosphere for which there is poor understanding of its adaptability to past warmer-than-present climate. Here we present observations from three sites in the region of interior Alaska and Yukon Territory that remained ice-free during Plio-Pleistocene glaciations, which collectively demonstrate the variable nature of the response of permafrost to warming during the last interglaciation. Chronology for all sites is based on identification of Old Crow tephra (OCt; 140±10 ka) by glass major element composition. Throughout the study region, OCt is consistently associated with organic-rich sediments that represent the last interglaciation on the basis of pollen, insect, and macrofossil assemblages. At the Palisades site on the Yukon River, 250 km west of Fairbanks, OCt is 1.5-3.5 m below thick (>1m) organic-rich silts and peats that are locally rich in beaver-chewed wood and large wood stumps, some of which are in growth position. In contrast, placer mining at Thistle Creek in central Yukon Territory exposes a dramatic thaw unconformity that is presumably related to local, but incomplete, permafrost degradation during the last interglaciation. In upslope positions at Thistle Creek, OCt is incorporated into a steeply dipping, 30 cm thick, organic-rich silt horizon that truncates at least one intact, relict ice wedge. The steeply dipping organic- rich horizon grades downslope into organic-rich silt with dense accumulations of wood fragments, including tree stems up to 2 m long. Evidence for similar permafrost degradation during the last

  19. Variation in mitochondrial DNA and allozymes discriminates early and late forms of Chinook salmon Oncorhynchus tshawytscha in the Kenai and Kasilof Rivers, AK

    USGS Publications Warehouse

    Adams, Noah S.; Spearman, William J.; Burger, Carl V.; Currens, Kenneth P.; Schreck, Carl B.; Li, Hiram W.

    1994-01-01

    Genetic differences between early and late forms of Alaskan chinook salmon (Oncorhynchus tshawytscha) were identified using two genetic approaches: mitochondrial DNA (mtDNA) analysis, and protein electrophoresis. Study populations consisted of early and late runs in each of the Kenai and Kasilof rivers in Alaska, and a population from the Minam River, Oregon. Two segments of mtDNA were amplified using the polymerase chain reaction (PCR) and digested with 14–16 restriction enzymes. Results showed that early runs were genetically similar to each other but different from the late runs. The late runs were different from each other based on the frequency of the common haplotypes. Frequency differences in shared haplotypes together with the presence of a unique haplotype separated the Minam River stock from those in Alaska. In the protein analysis, each population was examined at 30 allozyme loci. Based on 14 polymorphic loci, Minam River salmon were genetically distinct from the Alaskan populations. Within the Alaskan populations, early runs were most similar to each other but different from the late runs; the late runs were also genetically most similar to each other. Both mtDNA and allozyme analysis suggest that chinook salmon may segregate into genetically different early and late forms within a drainage.

  20. Alaskan Native High School Dropouts: A Report Prepared for Project ANNA.

    ERIC Educational Resources Information Center

    Jacobson, Desa

    Presented is a summary of the Alaskan Native high school dropouts. The data collected on 180 Native Alaskan high school dropouts was taken from the regional dormitories at Nome, Kodiak, Bethel and Boarding Home programs in Anchorage, Tok, Fairbanks, Dillingham, and Ketchikan. Students who terminated for academic reasons, failed to attend school,…

  1. Drilling and Testing the DOI041A Coalbed Methane Well, Fort Yukon, Alaska

    USGS Publications Warehouse

    Clark, Arthur; Barker, Charles E.; Weeks, Edwin P.

    2009-01-01

    The need for affordable energy sources is acute in rural communities of Alaska where costly diesel fuel must be delivered by barge or plane for power generation. Additionally, the transport, transfer, and storage of fuel pose great difficulty in these regions. Although small-scale energy development in remote Arctic locations presents unique challenges, identifying and developing economic, local sources of energy remains a high priority for state and local government. Many areas in rural Alaska contain widespread coal resources that may contain significant amounts of coalbed methane (CBM) that, when extracted, could be used for power generation. However, in many of these areas, little is known concerning the properties that control CBM occurrence and production, including coal bed geometry, coalbed gas content and saturation, reservoir permeability and pressure, and water chemistry. Therefore, drilling and testing to collect these data are required to accurately assess the viability of CBM as a potential energy source in most locations. In 2004, the U.S. Geological Survey (USGS) and Bureau of Land Management (BLM), in cooperation with the U.S. Department of Energy (DOE), the Alaska Department of Geological and Geophysical Surveys (DGGS), the University of Alaska Fairbanks (UAF), the Doyon Native Corporation, and the village of Fort Yukon, organized and funded the drilling of a well at Fort Yukon, Alaska to test coal beds for CBM developmental potential. Fort Yukon is a town of about 600 people and is composed mostly of Gwich'in Athabascan Native Americans. It is located near the center of the Yukon Flats Basin, approximately 145 mi northeast of Fairbanks.

  2. Biomarkers of contaminant exposure in northern pike (Esox lucius) from the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Hinck, J.E.; Blazer, V.S.; Denslow, N.D.; Myers, M.S.; Gross, T.S.; Tillitt, D.E.

    2007-01-01

    As part of a larger investigation, northern pike (n = 158; Esox lucius) were collected from ten sites in the Yukon River Basin (YRB), Alaska, to document biomarkers and their correlations with organochlorine pesticide (total p,p'-DDT, total chlordane, dieldrin, and toxaphene), total polychlorinated biphenyls (PCBs), and elemental contaminant (arsenic, cadmium, copper, lead, total mercury, selenium, and zinc) concentrations. A suite of biomarkers including somatic indices, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, vitellogenin concentrations, steroid hormone (17B- ustradiol and 16-kebtestosteront) concentrations, splenic macrophage aggregates (MAs), oocyte atresia, and other microscopic anomalies in various tissues were documented in YRB pike. Mean condition factor (0.50 to 0.68), hepatosomatic index (1.00% to 3.56%), and splenosomatic index (0.09% to 0.18%) were not anomalous at any site nor correlated with any contaminant concentration. Mean EROD activity (0.71 to 17.51 pmol/min/mg protein) was similar to basal activity levels previously measured in pike and was positively correlated with selenium concentrations (r = 0.88, P < 0.01). Vitellogenin concentrations in female (0.09 to 5.32 mg/mL) and male (0.01 mg/mL in male pike from multiple sites indicated exposure to estrogenic compounds. Mean steroid hormone concentrations and percent oocyte atresia were not anomalous in pike from any YRB site. Few site differences were significant for mean MA density (1.86 to 6.42 MA/mm2), size (812 to 1481 ??m2), and tissue occupied (MA-%; 0.24% to 0.75%). A linear regression between MA-% and total PCBs was significant, although PCB concentrations were generally low in YRB pike (???63 ng/g), and MA-% values in female pike (0.24% to 0.54%) were lower than in male pike (0.32% to 0.75%) at similar PCB concentrations. Greater numbers of MAs were found as zinc concentrations increased in YRB female pike, but it is unlikely that this is a causative relationship

  3. Pre-"peak water" time in the southwest Yukon: when cryospheric changes trigger hydrological regime shifts

    NASA Astrophysics Data System (ADS)

    Baraer, M.; Chesnokova, A.; Huh, K. I.; Laperriere-Robillard, T.

    2017-12-01

    Saint-Elias Mountains host numerous cryospheric systems such as glaciers, seasonal and perennial snow cover, permafrost, aufeis, and different forms of buried ice. Those systems are very sensitive to climate changes and exhibit ongoing reduction in extent and/or changes in formation/ablation times. Because they highly influence the hydrological regimes of rivers, cryospheric changes raise concerns about consequences for regional water resources and ecosystems. The present study combines historical data analysis and hydrological modeling in order to estimate how cryospheric changes impact hydrological regimes at eight watersheds of different glacier cover (0- 30%) in the southwest Yukon. Methods combine traditional hydrograph analysis techniques and more advance techniques such as Fast Fourier Transform filters used to isolate significant trends in discharge properties from noise or climatic oscillations. Measured trends in discharge variables are connected to cryospheric changes by using a water balance / peak water model (Baraer et al., 2012), here adapted to the main cryospheric systems that characterize the southwest Yukon.Results show three distinct hydrological regimes for (1) non glacierized, (2) glacierized, and (3) major lakes hosting catchments. The studied glacierized catchments have not passed the "peak water" yet and still exhibit increases in yearly and late summer discharges and a decrease in runoff variability. All watersheds show an increase in winter discharge and a snowmelt-driven shift of yearly peak discharge toward earlier in the season. The study suggests that, in a couple of decades, water resources and dependent ecosystems will face the combined effects of (A) a shift in the contribution trend from declining perennial cryospheric systems and (B) continuing alteration of the contribution from the seasonal cryospheric systems.

  4. Nitrogen isotopes suggest a change in nitrogen dynamics between the Late Pleistocene and modern time in Yukon, Canada

    PubMed Central

    Longstaffe, Fred J.; Zazula, Grant

    2018-01-01

    A magnificent repository of Late Pleistocene terrestrial megafauna fossils is contained in ice-rich loess deposits of Alaska and Yukon, collectively eastern Beringia. The stable carbon (δ13C) and nitrogen (δ15N) isotope compositions of bone collagen from these fossils are routinely used to determine paleodiet and reconstruct the paleoecosystem. This approach requires consideration of changes in C- and N-isotope dynamics over time and their effects on the terrestrial vegetation isotopic baseline. To test for such changes between the Late Pleistocene and modern time, we compared δ13C and δ15N for vegetation and bone collagen and structural carbonate of some modern, Yukon, arctic ground squirrels with vegetation and bones from Late Pleistocene fossil arctic ground squirrel nests preserved in Yukon loess deposits. The isotopic discrimination between arctic ground squirrel bone collagen and their diet was measured using modern samples, as were isotopic changes during plant decomposition; Over-wintering decomposition of typical vegetation following senescence resulted in a minor change (~0–1 ‰) in δ13C of modern Yukon grasses. A major change (~2–10 ‰) in δ15N was measured for decomposing Yukon grasses thinly covered by loess. As expected, the collagen-diet C-isotope discrimination measured for modern samples confirms that modern vegetation δ13C is a suitable proxy for the Late Pleistocene vegetation in Yukon Territory, after correction for the Suess effect. The N-isotope composition of vegetation from the fossil arctic ground squirrel nests, however, is determined to be ~2.8 ‰ higher than modern grasslands in the region, after correction for decomposition effects. This result suggests a change in N dynamics in this region between the Late Pleistocene and modern time. PMID:29447202

  5. Nitrogen isotopes suggest a change in nitrogen dynamics between the Late Pleistocene and modern time in Yukon, Canada.

    PubMed

    Tahmasebi, Farnoush; Longstaffe, Fred J; Zazula, Grant

    2018-01-01

    A magnificent repository of Late Pleistocene terrestrial megafauna fossils is contained in ice-rich loess deposits of Alaska and Yukon, collectively eastern Beringia. The stable carbon (δ13C) and nitrogen (δ15N) isotope compositions of bone collagen from these fossils are routinely used to determine paleodiet and reconstruct the paleoecosystem. This approach requires consideration of changes in C- and N-isotope dynamics over time and their effects on the terrestrial vegetation isotopic baseline. To test for such changes between the Late Pleistocene and modern time, we compared δ13C and δ15N for vegetation and bone collagen and structural carbonate of some modern, Yukon, arctic ground squirrels with vegetation and bones from Late Pleistocene fossil arctic ground squirrel nests preserved in Yukon loess deposits. The isotopic discrimination between arctic ground squirrel bone collagen and their diet was measured using modern samples, as were isotopic changes during plant decomposition; Over-wintering decomposition of typical vegetation following senescence resulted in a minor change (~0-1 ‰) in δ13C of modern Yukon grasses. A major change (~2-10 ‰) in δ15N was measured for decomposing Yukon grasses thinly covered by loess. As expected, the collagen-diet C-isotope discrimination measured for modern samples confirms that modern vegetation δ13C is a suitable proxy for the Late Pleistocene vegetation in Yukon Territory, after correction for the Suess effect. The N-isotope composition of vegetation from the fossil arctic ground squirrel nests, however, is determined to be ~2.8 ‰ higher than modern grasslands in the region, after correction for decomposition effects. This result suggests a change in N dynamics in this region between the Late Pleistocene and modern time.

  6. Decline in a population of spectacled eiders nesting on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Ely, Craig R.; Dau, Christian; Babcock, Christopher

    1994-01-01

    The number of spectacled eiders nesting on two study areas near the Kashunuk River, on the central Yukon-Kuskokwim (Y-K) Delta, Alaska, declined by over 75% in the last 20 years. Nesting densities have remained low, but have not significantly declined since 1985. There has been no decrease in the reproductive effort of individual females as indicated by average clutch sizes. There has been a significant decline in the proportion of nests located on islands on one of the two study areas. Nesting success declined significantly during the 1970's. Success was not monitored in recent years, but has likely been low, based on the poor nesting success and declining numbers of cackling Canada geese and black brant nesting on the area. Nest predation by arctic foxes severely limited the productivity of cackling Canada geese, and foxes were likely the major predators of eider nests. Persistent high predation rates may lead to local extirpation in highly philopatric species such as eiders.

  7. Defining biophysical reference conditions for dynamics river systems: an Alaskan example

    NASA Astrophysics Data System (ADS)

    Pess, G. R.

    2008-12-01

    Defining reference conditions for dynamic river ecosystems is difficult for two reasons. First long-term, persistent anthropogenic influences such as land development, harvest of biological resources, and invasive species have resulted in degraded, reduced, and simplified ecological communities and associated habitats. Second, river systems that have not been altered through human disturbance rarely have a long-term dataset on ecological conditions. However there are exceptions which can help us define the dynamic nature of river ecosystems. One large-scale exception is the Wood River system in Bristol Bay, Alaska, where habitat and salmon populations have not been altered by anthropogenic influences such as land development, hatchery production, and invasive species. In addition, the one major anthropogenic disturbance, salmon (Oncorhynchus spp.) harvest, has been quantified and regulated since its inception. First, we examined the variation in watershed and stream habitat characteristics across the Wood River system. We then compared these stream habitat characteristics with data that was collected in the 1950s. Lastly, we examined the correlation between pink (Oncorhynchus gorbuscha), chum (O. keta), and Chinook (O. tshawytscha), and sockeye salmon (O. nerka), and habitat characteristics in the Wood River system using four decades of data on salmon. We found that specific habitat attributes such as stream channel wetted width, depth, cover type, and the proportion of spawnable area were similar to data collected in the 1950s. Greater stream habitat variation occurred among streams than over time. Salmon occurrence and abundance, however was more temporal and spatially variable. The occurrence of pink and chum salmon increased from the 1970's to the present in the Wood River system, while sockeye abundance has fluctuated with changes in ocean conditions. Pink, Chinook and chum salmon ranged from non-existent to episodic to abundantly perennial, while sockeye

  8. Abundance, size distributions and trace-element binding of organic and iron-rich nanocolloids in Alaskan rivers, as revealed by field-flow fractionation and ICP-MS

    NASA Astrophysics Data System (ADS)

    Stolpe, Björn; Guo, Laodong; Shiller, Alan M.; Aiken, George R.

    2013-03-01

    Water samples were collected from six small rivers in the Yukon River basin in central Alaska to examine the role of colloids and organic matter in the transport of trace elements in Northern high latitude watersheds influenced by permafrost. Concentrations of dissolved organic carbon (DOC), selected elements (Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Ba, Pb, U), and UV-absorbance spectra were measured in 0.45 μm filtered samples. 'Nanocolloidal size distributions' (0.5-40 nm, hydrodynamic diameter) of humic-type and chromophoric dissolved organic matter (CDOM), Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb were determined by on-line coupling of flow field-flow fractionation (FFF) to detectors including UV-absorbance, fluorescence, and ICP-MS. Total dissolved and nanocolloidal concentrations of the elements varied considerably between the rivers and between spring flood and late summer base flow. Data on specific UV-absorbance (SUVA), spectral slopes, and the nanocolloidal fraction of the UV-absorbance indicated a decrease in aromaticity and size of CDOM from spring flood to late summer. The nanocolloidal size distributions indicated the presence of different 'components' of nanocolloids. 'Fulvic-rich nanocolloids' had a hydrodynamic diameter of 0.5-3 nm throughout the sampling season; 'organic/iron-rich nanocolloids' occurred in the <8 nm size range during the spring flood; whereas 'iron-rich nanocolloids' formed a discrete 4-40 nm components during summer base flow. Mn, Co, Ni, Cu and Zn were distributed between the nanocolloid components depending on the stability constant of the metal (+II)-organic complexes, while stronger association of Cr to the iron-rich nanocolloids was attributed to the higher oxidation states of Cr (+III or +IV). Changes in total dissolved element concentrations, size and composition of CDOM, and occurrence and size of organic/iron and iron-rich nanocolloids were related to variations in their sources from either the upper organic

  9. Leaf cuticular lipids on the Shandong and Yukon ecotypes of saltwater cress, Eutrema salsugineum, and their response to water deficiency and impact on cuticle permeability.

    PubMed

    Xu, Xiaojing; Feng, Jinchao; Lü, Shiyou; Lohrey, Greg T; An, Huiling; Zhou, Yijun; Jenks, Matthew A

    2014-08-01

    The impact of water-deficit stress on leaf cuticular waxes and cutin monomers, and traits associated with cuticle permeability were examined in Shandong and Yukon ecotypes of Eutrema salsugineum (syn. Thellungiella salsuginea). Although Shandong exhibits glaucous leaves, and Yukon is non-glaucous, wax amounts on non-stressed Yukon leaves were 4.6-fold higher than on Shandong, due mainly to Yukon's eightfold higher wax fatty acids, especially the C22 and C24 acid homologues. Water deficit caused a 26.9% increase in total waxes on Shandong leaves, due mainly to increased C22 and C24 acids; and caused 10.2% more wax on Yukon, due mainly to an increase in wax alkanes. Total cutin monomers on non-stressed leaves of Yukon were 58.3% higher than on Shandong. Water deficit caused a 28.2% increase in total cutin monomers on Shandong, whereas total cutin monomers were not induced on Yukon. With or without stress, more abundant cuticle lipids were generally associated with lower water loss rates, lower chlorophyll efflux rates and an extended time before water deficit-induced wilting. In response to water deficit, Shandong showed elevated transcription of genes encoding elongase subunits, consistent with the higher stress induction of acids by Shandong. Yukon's higher induction of CER1 and CER3 transcripts may explain why alkanes increased most on Yukon after water deficit. Eutrema, with its diverse cuticle lipids and responsiveness, provides a valuable genetic resource for identifying new genes and alleles effecting cuticle metabolism, and lays groundwork for studies of the cuticle's role in extreme stress tolerance. Published 2013. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

  10. Transformation of Upland Water and Carbon Dynamics by Thawing Permafrost in the Alaskan Interior

    NASA Astrophysics Data System (ADS)

    Ewing, S. A.; Paces, J. B.; O'Donnell, J. A.; Kanevskiy, M. Z.; Shur, Y.; Jorgenson, M. T.; Harden, J.; Aiken, G. R.; Striegl, R.

    2009-05-01

    Large arctic rivers can provide an integrated signal of regional permafrost thaw and associated carbon dynamics. A long-term (30-y) decrease in dissolved organic carbon (DOC) and increase in dissolved inorganic carbon in the Yukon River Basin (YRB) suggest increased flow through mineral soils as a result of permafrost thaw. We used U series isotopes to test for the influence of thaw on soil and surface waters in small upland catchments at two sites within the YRB. In natural waters, 234U/238U activity ratios exceed 1.00 (secular equilibrium) as a function of water-rock contact time. Previous work has shown that in major YRB rivers, seasonally and spatially variable 234U/238U ratios could indicate both groundwater inputs and permafrost thaw, with ratios ranging from 1.1 to 2.6. We show that 234U/238U ratios in soil and surface water from these small catchments span the range of values observed in the major rivers, and indicate greater influence of older water where the mineral soil and underlying sediment facilitate drainage and permafrost degradation. Analysis of deep, ice-rich loess permafrost cores (2-10 m) reveals that thaw of Pleistocene ice can release high concentrations of DOC (>1000 ppm) and ammonium in thaw waters. The age and chemical composition of these waters allows for improved prediction of downstream carbon dynamics upon thaw. Field observation of hillslope soil sequences indicates that both topography and mineral substrate influence the effects of thaw on water and carbon dynamics in small catchments.

  11. Cancer mortality in Yukon 1999–2013: elevated mortality rates and a unique cancer profile

    PubMed Central

    Simkin, Jonathan; Woods, Ryan; Elliott, Catherine

    2017-01-01

    ABSTRACT Background: Although cancer is the leading cause of death in Canada, cancer in the North has been incompletely described. Objective: To determine cancer mortality rates in the Yukon Territory, compare them with Canadian rates, and identify major causes of cancer mortality. Design: The Yukon Vital Statistics Registry provided all cancer deaths for Yukon residents between 1999-2013. Age-standardised mortality rates (ASMRs) were calculated using direct standardisation and compared with Canadian rates. Standardised mortality ratios (SMRs) were calculated using indirect standardisation relative to age-specific rates from Canada, British Columbia (BC), and three sub-provincial BC administrative health regions : Interior Health (IH), Northern Health (NH) and Vancouver Coastal Health (VCH). Trends in smoothed ASMRs were examined with graphical methods. Results: Yukon’s all-cancer ASMRs were elevated compared with national and provincial rates for the entire period. Disparities were greatest compared with the urban VCH: prostate (SMRVCH=246.3, 95% CI 140.9–351.6), female lung (SMRVCH=221.2, 95% CI 154.3–288.1), female breast (SMRVCH=169.0 95% CI, 101.4–236.7), and total colorectal (SMRVCH=149.3, 95% CI 101.8–196.8) cancers were significantly elevated. Total stomach cancer mortality was significantly elevated compared with all comparators. Conclusions: Yukon cancer mortality rates were elevated compared with national, provincial, urban, and southern-rural jurisdictions. More research is required to elucidate these differences. PMID:28598269

  12. The Mackenzie River magnetic anomaly, Yukon and Northwest Territories, Canada-Evidence for Early Proterozoic magmatic arc crust at the edge of the North American craton

    USGS Publications Warehouse

    Pilkington, M.; Saltus, R.W.

    2009-01-01

    We characterize the nature of the source of the high-amplitude, long-wavelength, Mackenzie River magnetic anomaly (MRA), Yukon and Northwest Territories, Canada, based on magnetic field data collected at three different altitudes: 300??m, 3.5??km and 400??km. The MRA is the largest amplitude (13??nT) satellite magnetic anomaly over Canada. Within the extent of the MRA, source depth estimates (8-12??km) from Euler deconvolution of low-altitude aeromagnetic data show coincidence with basement depths interpreted from reflection seismic data. Inversion of high-altitude (3.5??km) aeromagnetic data produces an average magnetization of 2.5??A/m within a 15- to 35-km deep layer, a value typical of magmatic arc complexes. Early Proterozoic magmatic arc rocks have been sampled to the southeast of the MRA, within the Fort Simpson magnetic anomaly. The MRA is one of several broad-scale magnetic highs that occur along the inboard margin of the Cordillera in Canada and Alaska, which are coincident with geometric changes in the thrust front transition from the mobile belt to stable cratonic North America. The inferred early Proterozoic magmatic arc complex along the western edge of the North American craton likely influenced later tectonic evolution, by acting as a buttress along the inboard margin of the Cordilleran fold-and-thrust belt. Crown Copyright ?? 2008.

  13. Recent U.S. Geological Survey Studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada-Results of a 5-Year Project

    USGS Publications Warehouse

    Gough, Larry P.; Day, Warren C.

    2010-01-01

    This report presents summary papers of work conducted between 2002 and 2007 under a 5-year project effort funded by the U.S. Geological Survey Mineral Resources Program, formerly entitled 'Tintina Metallogenic Province: Integrated Studies on Geologic Framework, Mineral Resources, and Environmental Signatures.' As the project progressed, the informal title changed from 'Tintina Metallogenic Province' project to 'Tintina Gold Province' project, the latter being more closely aligned with the terminology used by the mineral industry. As Goldfarb and others explain in the first chapter of this report, the Tintina Gold Province is a convenient term used by the mineral exploration community for a 'region of very varied geology, gold deposit types, and resource potential'. The Tintina Gold Province encompasses roughly 150,000 square kilometers, bounded by the Kaltag-Tintina fault system on the north and the Farewell-Denali fault system on the south. It extends westward in a broad arc, some 200 km wide, from northernmost British Columbia, through the Yukon, through southeastern and central Alaska, to southwestern Alaska. The climate is subarctic and, in Alaska, includes major physiographic delineations and ecoregions such as the Yukon-Tanana Upland, Tanana-Kuskokwim Lowlands, Yukon River Lowlands, and the Kuskokwim Mountains. Although the Tintina Gold Province is historically important for some of the very first placer and lode gold discoveries in northern North America, it has recently seen resurgence in mineral exploration, development, and mining activity. This resurgence is due to both new discoveries (for example, Pogo and Donlin Creek) and to the application of modern extraction methods to previously known, but economically restrictive, low-grade, bulk-tonnage gold resources (for example, Fort Knox, Clear Creek, and Scheelite Dome). In addition, the Tintina Gold Province hosts numerous other mineral deposit types, possessing both high and low sulfide content, which

  14. A molecular comparison of Alaskan and North East Atlantic Halicondria panicea (Pallas 1766) (Porifera: Demospongiae)

    USGS Publications Warehouse

    Erpenbeck, Dirk; Knowlton, Anne L.; Talbot, Sandra L.; Highsmith, Ray C.; van Soest, Rob W.M.

    2004-01-01

    The intraspecific relationships between populations of Alaskan Halichondria cf. panicea are the subjects of ongoing research. In this study we compare CO1 sequences of Alaskan Halichondria cf. panicea with North East Atlantic Halichondria panicea and its sister species Halichondria bowerbanki. Alaskan Halichondria cf. panicea form a well-supported sister group to the European Halichondria panicea/ H. bowerbanki species complex in the resulting gene tree and cluster distantly from their European conspecifics.

  15. Carbon balance of the Alaskan boreal forest

    Treesearch

    John Yarie; Tim Hammond

    1996-01-01

    Determination of the carbon balance in a broad forest region like the Alaskan boreal forest requires the development of a number of important environmental (state factors) classes to allow for the development of carbon balance estimates.

  16. 75 FR 29582 - Yukon Flats National Wildlife Refuge, Fairbanks, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R7-R-2010-N082; 70133-1265-0000-U4] Yukon Flats National Wildlife Refuge, Fairbanks, AK AGENCY: U.S. Fish and Wildlife Service, Interior. ACTION: Notice of availability: record of decision. SUMMARY: We, the U.S. Fish and Wildlife Service...

  17. An Authentic Voice in the Technocratic Wilderness: Alaskan Natives and the "Tundra Times."

    ERIC Educational Resources Information Center

    Daley, Patrick; James, Beverly

    1986-01-01

    Examines a pair of critical challenges to the cultural integrity of Alaskan Natives around 1960 as pivotal episodes in the process of native resistance to U. S. dominance. Historically evaluates the fragility of native culture in terms of the political, scientific, and economic interests expressed in the mainstream Alaskan press, particularly the…

  18. Genetics, recruitment, and migration patterns of Arctic Cisco (Coregonus autumnalis) in the Colville River, Alaska and Mackenzie River, Canada

    USGS Publications Warehouse

    Zimmerman, Christian E.; Ramey, Andy M.; Turner, S.; Mueter, Franz J.; Murphy, S.; Nielsen, Jennifer L.

    2013-01-01

    Arctic cisco Coregonus autumnalis have a complex anadromous life history, many aspects of which remain poorly understood. Some life history traits of Arctic cisco from the Colville River, Alaska, and Mackenzie River basin, Canada, were investigated using molecular genetics, harvest data, and otolith microchemistry. The Mackenzie hypothesis, which suggests that Arctic cisco found in Alaskan waters originate from the Mackenzie River system, was tested using 11 microsatellite loci and a single mitochondrial DNA gene. No genetic differentiation was found among sample collections from the Colville River and the Mackenzie River system using molecular markers (P > 0.19 in all comparisons). Model-based clustering methods also supported genetic admixture between sample collections from the Colville River and Mackenzie River basin. A reanalysis of recruitment patterns to Alaska, which included data from recent warm periods and suspected changes in atmospheric circulation patterns, still finds that recruitment is correlated to wind conditions. Otolith microchemistry (Sr/Ca ratios) confirmed repeated, annual movements of Arctic cisco between low-salinity habitats in winter and marine waters in summer.

  19. A genetic dissection of breed composition and performance enhancement in the Alaskan sled dog

    PubMed Central

    2010-01-01

    Background The Alaskan sled dog offers a rare opportunity to investigate the development of a dog breed based solely on performance, rather than appearance, thus setting the breed apart from most others. Several established breeds, many of which are recognized by the American Kennel Club (AKC), have been introduced into the sled dog population to enhance racing performance. We have used molecular methods to ascertain the constitutive breeds used to develop successful sled dog lines, and in doing so, determined the breed origins of specific performance-related behaviors. One hundred and ninety-nine Alaskan sled dogs were genotyped using 96 microsatellite markers that span the canine genome. These data were compared to that from 141 similarly genotyped purebred dog breeds. Sled dogs were evaluated for breed composition based on a variety of performance phenotypes including speed, endurance and work ethic, and the data stratified based on population structure. Results We observe that the Alaskan sled dog has a unique molecular signature and that the genetic profile is sufficient for identifying dogs bred for sprint versus distance. When evaluating contributions of existing breeds we find that the Alaskan Malamute and Siberian Husky contributions are associated with enhanced endurance; Pointer and Saluki are associated with enhanced speed and the Anatolian Shepherd demonstrates a positive influence on work ethic. Conclusion We have established a genetic breed profile for the Alaskan sled dog, identified profile variance between sprint and distance dogs, and established breeds associated with enhanced performance attributes. These data set the stage for mapping studies aimed at finding genes that are associated with athletic attributes integral to the high performing Alaskan sled dog. PMID:20649949

  20. Protolith relations of the Gravina belt and Yukon-Tanana terrane in central southeastern Alaska

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McClelland, W.C.; Gehrels, G.E.; Patchett, P.J.

    1992-01-01

    Metamorphic rocks west of the Coast Mountains batholith in central southeastern Alaska are divided into the Gravina belt, Taku terrane, and newly defined Ruth assemblage. The Ruth assemblage comprises metapelite, quartzose metaclastic strata, quartzite, marble, felsic metatuff, mafic metavolcanic rocks, and orthogneiss. Depositional and emplacement ages of 367 {plus minus} 10 Ma and 345 {plus minus} 13 Ma inferred from discordant U/Pb zircon analyses on felsic metatuff and granodioritic orthogneiss, respectively, require that at least portions of the Ruth assemblage be Late Devonian and early Mississippian in age. The assemblage is similar in age and protolith to, and thus correlatedmore » with, the Yukon-Tanana terrane. The Gravina belt is characterized by upper Jurassic and lower Cretaceous mafic volcanic rocks and tuffaceous turbiditic clastic strata that unconformably overlie the Alexander terrane. Metamorphic rocks that structurally underlie the Taku terrane and Rugh assemblage are included in this assemblage. Trace element geochemistry and the abundance of pyroclastic flows associated with tuffaceous turbidites suggest that the Gravina belt evolved in an intra-arc basinal setting. In central southeastern Alaska, the mid-Cretaceous structure that currently separates the Ruth assemblage (Yukon-Tanana correlative) from the Gravina belt marks the fundamental boundary between the Alexander-Wrangellia terrane and inboard Yukon-Tanana and Stikine terranes.« less

  1. Reconstructing satellite images to quantify spatially explicit land surface change caused by fires and succession: A demonstration in the Yukon River Basin of interior Alaska

    USGS Publications Warehouse

    Huang, Shengli; Jin, Suming; Dahal, Devendra; Chen, Xuexia; Young, Claudia; Liu, Heping; Liu, Shuguang

    2013-01-01

    Land surface change caused by fires and succession is confounded by many site-specific factors and requires further study. The objective of this study was to reveal the spatially explicit land surface change by minimizing the confounding factors of weather variability, seasonal offset, topography, land cover, and drainage. In a pilot study of the Yukon River Basin of interior Alaska, we retrieved Normalized Difference Vegetation Index (NDVI), albedo, and land surface temperature (LST) from a postfire Landsat image acquired on August 5th, 2004. With a Landsat reference image acquired on June 26th, 1986, we reconstructed NDVI, albedo, and LST of 1987–2004 fire scars for August 5th, 2004, assuming that these fires had not occurred. The difference between actual postfire and assuming-no-fire scenarios depicted the fires and succession impact. Our results demonstrated the following: (1) NDVI showed an immediate decrease after burning but gradually recovered to prefire levels in the following years, in which burn severity might play an important role during this process; (2) Albedo showed an immediate decrease after burning but then recovered and became higher than prefire levels; and (3) Most fires caused surface warming, but cooler surfaces did exist; time-since-fire affected the prefire and postfire LST difference but no absolute trend could be found. Our approach provided spatially explicit land surface change rather than average condition, enabling a better understanding of fires and succession impact on ecological consequences at the pixel level.

  2. Geochemical evidences of methane hydrate dissociation in Alaskan Beaufort Margin during Holocene

    NASA Astrophysics Data System (ADS)

    Uchida, M.; Rella, S.; Kubota, Y.; Kumata, H.; Mantoku, K.; Nishino, S.; Itoh, M.

    2017-12-01

    Alaskan Beaufort margin bear large abundances of sub-sea and permafrost methane hydrate[Ruppel, 2016]. During the Last Glacial, previous reported direct and indirect evidences accumulated from geochemical data from marginal sea sediment suggests that methane episodically released from hydrate trapped in the seafloor sediments[Kennett et al., 2000; Uchida et al., 2006, 2008; Cook et al, 2011]. Here we analyzed stable isotopes of foraminifera and molecular marker derived from the activity of methanotrophic bacteria from piston cores collected by the 2010 R/V Mirai cruise in Alaskan Beaufort Margin. Our data showed highly depleted 13C compositions of benthic foraminifera, suggesting indirect records of enhanced incorporation of 13C-depleted CO2 formed by methanotrophic process that use 12C-enriched methane as their main source of carbon. This is the first evidence of methane hydrate dissociation in Alaskan margin. Here we discussed timing of signals of methane dissociation with variability of sea ice and intermediate Atlantic water temperature. The dissociation of methane hydrate in the Alaskan Margin may be modulated by Atlantic warm intermediate water warming. Our results suggest that Arctic marginal regions bearing large amount methane hydrate may be a profound effect on future warming climate changes.

  3. Characteristics of fall chum salmon spawning habitat on a mainstem river in Interior Alaska

    USGS Publications Warehouse

    Burril, Sean E.; Zimmerman, Christian E.; Finn, James E.

    2010-01-01

    Chum salmon (Oncorhynchus keta) are the most abundant species of salmon spawning in the Yukon River drainage system, and they support important personal use, subsistence, and commercial fisheries. Chum salmon returning to the Tanana River in Interior Alaska are a significant contribution to the overall abundance of Yukon River chum salmon and an improved understanding of habitat use is needed to improve conservation of this important resource. We characterized spawning habitat of chum salmon using the mainstem Tanana River as part of a larger study to document spawning distributions and habitat use in this river. Areas of spawning activity were located using radiotelemetry and aerial helicopter surveys. At 11 spawning sites in the mainstem Tanana River, we recorded inter-gravel and surface-water temperatures and vertical hydraulic gradient (an indication of the direction of water flux) in substrate adjacent to salmon redds. At all locations, vertical hydraulic gradient adjacent to redds was positive, indicating that water was upwelling through the gravel. Inter-gravel temperatures adjacent to redds generally were warmer than surface water at most locations and were more stable than surface-water temperature. Inter-gravel water temperature adjacent to redds ranged from 2.6 to 5.8 degrees Celsius, whereas surface-water temperature ranged from greater than 0 to 5.5 degrees Celsius. Some sites were affected more by extremes in air temperature than others. At these sites, inter-gravel water temperature profiles were variable (with ranges similar to those observed in surface water), suggesting that even though upwelling habitats provide a stable thermal incubation environment, eggs and embryos still may be affected by extremes in air temperature. Fine sand and silt covered redds at multiple sites and were evidence of increased river flow during the winter months, which may be a potential source of increased mortality during egg-to-fry development. This study provides

  4. Impacts of fire on nitrogen cycling in aquatic and terrestrial ecosystems in the Yukon-Kuskokwim River Delta, AK

    NASA Astrophysics Data System (ADS)

    Schade, J. D.; Jardine, L. E.; Bristol, E. M.; Navarro-Perez, E.; Melton, S.; Jimmie, J. A.; Natali, S.; Mann, P. J.; Holmes, R. M.

    2016-12-01

    Global climate change is having a disproportionate impact on northern high latitudes, including rapid increases in temperature, changes in precipitation, and increasing fire frequency and severity. Wildfires have been shown to strongly influence ecosystem processes through acceleration of permafrost thaw and increased nitrogen (N) availability, the effects of which may increase gaseous loss of carbon (C) to the atmosphere, increase primary production by alleviating N limitation, or both. The extent of these fire impacts has not been well-documented in the Arctic, particularly in areas of discontinuous permafrost. In 2015, the Yukon-Kuskokwim River Delta (YK Delta) in southwestern Alaska experienced the largest fire season in recorded history, providing an opportunity to study wildfire impacts on an area particularly vulnerable to permafrost thaw. Our objectives were to study the impacts of these fires on nitrogen availability in a range of land cover classes, including peat plateaus, channel fens, and aquatic ecosystems distributed across the landscapes. We sampled soils from several vegetation patches on burned and unburned peat plateaus, and soil and surface waters from fens, small ponds, and streams downslope of these sites. All water samples were filtered through GFF filters in the field. Soils were transported frozen to the Woods Hole Research Center and extracted in KCl. All water samples and extracts were analyzed for NH4 and NO3 concentrations. We found substantially higher concentrations of extractable NH4 in burned soils, but very little extractable NO3 in either burned or unburned soils. Water samples also showed higher NH4 in aquatic ecosystems in burned watersheds, but, in contrast to soils, showed relatively high NO3 concentrations, particularly in waters from lower landscape positions. Overall, aquatic ecosystems exhibited higher NO3: NH4 ratios than soil extractions, and increasing NO3: NH4 downslope. These results suggest significant export of

  5. Impacts of fire on nitrogen cycling in aquatic and terrestrial ecosystems in the Yukon-Kuskokwim River Delta, AK

    NASA Astrophysics Data System (ADS)

    Schade, J. D.; Jardine, L. E.; Bristol, E. M.; Navarro-Perez, E.; Melton, S.; Jimmie, J. A.; Natali, S.; Mann, P. J.; Holmes, R. M.

    2017-12-01

    Global climate change is having a disproportionate impact on northern high latitudes, including rapid increases in temperature, changes in precipitation, and increasing fire frequency and severity. Wildfires have been shown to strongly influence ecosystem processes through acceleration of permafrost thaw and increased nitrogen (N) availability, the effects of which may increase gaseous loss of carbon (C) to the atmosphere, increase primary production by alleviating N limitation, or both. The extent of these fire impacts has not been well-documented in the Arctic, particularly in areas of discontinuous permafrost. In 2015, the Yukon-Kuskokwim River Delta (YK Delta) in southwestern Alaska experienced the largest fire season in recorded history, providing an opportunity to study wildfire impacts on an area particularly vulnerable to permafrost thaw. Our objectives were to study the impacts of these fires on nitrogen availability in a range of land cover classes, including peat plateaus, channel fens, and aquatic ecosystems distributed across the landscapes. We sampled soils from several vegetation patches on burned and unburned peat plateaus, and soil and surface waters from fens, small ponds, and streams downslope of these sites. All water samples were filtered through GFF filters in the field. Soils were transported frozen to the Woods Hole Research Center and extracted in KCl. All water samples and extracts were analyzed for NH4 and NO3 concentrations. We found substantially higher concentrations of extractable NH4 in burned soils, but very little extractable NO3 in either burned or unburned soils. Water samples also showed higher NH4 in aquatic ecosystems in burned watersheds, but, in contrast to soils, showed relatively high NO3 concentrations, particularly in waters from lower landscape positions. Overall, aquatic ecosystems exhibited higher NO3: NH4 ratios than soil extractions, and increasing NO3: NH4 downslope. These results suggest significant export of

  6. Mountain Permafrost in the Yukon Territory, Canada: Mapping and Modelling

    NASA Astrophysics Data System (ADS)

    Lewkowicz, A. G.; Bonnaventure, P.; Schultz, E.; Etzelmuller, B.

    2006-12-01

    The distribution and characteristics of mountain permafrost in North America are poorly known compared to lowland permafrost, and predictions of climatic change impacts are therefore subject to a higher degree of uncertainty. Recent DC resistivity soundings in association with borehole temperature information in the Yukon Territory, show the wide range of permafrost conditions that can exist at sites separated by short distances. To provide baseline information for future modelling, efforts are underway to produce a detailed map of permafrost probability in the mountains of the southern half of the Yukon Territory (60-65°N), an area greater than 200 x 103km2. The methodology is based on the Basal Temperature of Snow (BTS) technique, first developed in the European Alps. Ground surface temperatures measured at the base of snow > 80 cm thick in late winter are an indicator of permafrost presence or absence. We have used this method successfully in three study areas of about 200 km2: first, Wolf Creek basin near Whitehorse (Lewkowicz and Ednie, 2004) and now the western side of the Ruby Range adjacent to Kluane Lake, and the Haines Summit area in northwestern British Columbia. In each area, (1) we installed miniature temperature loggers at the ground surface and in the air to check on the timing of the BTS measurements; (2) we measured BTS values in the elevation zone across which permafrost was expected to become widespread; (3) we modelled the BTS spatial field using elevation (from a 30 m DEM) and potential incoming solar radiation (PISR) as the independent variables; and (4) we used logistic regression to compare the modelled BTS values with pit observations made in late-summer of the presence or absence of frozen ground. Both elevation and PISR were significant in the Wolf Creek and Ruby Range sites which have relatively continental climates and fall within the Upper Yukon-Stikine Basin climatic region (Wahl et al., 1987). For the Haines Summit area, however

  7. 33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

  8. 33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

  9. 33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

  10. 33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

  11. 33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

  12. A retrospective on hydroacoustic assessment of fish passage in Alaskan rivers

    NASA Astrophysics Data System (ADS)

    Burwen, Debby; Fleischman, Steve; Maxwell, Suzanne; Pfisterer, Carl

    2005-04-01

    The Alaska Department of Fish and Game (ADFG) has enumerated fish stocks in rivers for over 30 years using a variety of acoustic technologies including single-, dual-, and split-beam sonar. Most recently, ADFG has evaluated a relatively new sonar technology at several sites in Alaska to determine its applicability to counting migrating fish in rivers. The new system, called a Dual frequency IDentification SONar (DIDSON), is a high-definition imaging sonar designed and manufactured by the University of Washington's Applied Physics Lab for military applications such as diver detection and underwater mine identification. Results from experiments conducted in 2002-2004 indicate that DIDSON provides significant improvements in our ability to detect, track, and determine the direction of travel of migrating fish in rivers. One of the most powerful uses of the DIDSON has been to combine its camera-like images of fish swimming behavior with corresponding split-beam data. These linked datasets have allowed us to evaluate the effects of fish orientation and swimming behavior on echo shape parameters that have proven useful in the classification of certain fish species.

  13. Engaging Alaskan Students in Cryospheric Research

    NASA Astrophysics Data System (ADS)

    Yoshikawa, K.; Sparrow, E. B.; Kopplin, M.

    2011-12-01

    The Permafrost/Active Layer Monitoring Program is an ongoing project, which builds on work begun in 2005 to establish long-term permafrost and active layer monitoring sites adjacent to schools in Alaskan communities and in the circumpolar permafrost region. Currently, there are about 200 schools in Alaska involved in the project including also Denali National Park and Preserve. The project has both scientific and outreach components. The monitoring sites collect temperature data on permafrost, and the length and depth of the active layer (the layer above the permafrost that thaws during summer and freezes again during winter). To ensure scientific integrity, the scientist installed all of the monitoring instruments and selected the sites representative of the surrounding biome and thermal conditions. This is a unique collaboration opportunity in that 1) uses scientifically accurate instruments, 2) is scientist led and supervised including instrumentation set-up and data quality check, 3)has teacher/student organized observation network, 4) increased spatial scale of monitoring sites that covers all of the Alaskan communities. Most of the monitoring sites are located in remote communities, where the majority of residents depend on a subsistence lifestyle. Changes in climate, length of seasons, and permafrost conditions directly impact natural resources and subsistence activities. Changes in permafrost conditions also affect local ecosystems and hydrological regimes, and can influence the severity of natural disasters. In addition to extending our knowledge of the arctic environment, the program involves school-age students. Several students have been using the data for their projects and have been inspired to continue their studies. The data gathered from these stations are shared with other schools and made available to the public through our web site (http://www.uaf.edu/permafrost). Also communities have increasingly become interested in this project not only as

  14. Forecast Tools for Alaska River Ice Breakup Timing and Severity

    NASA Astrophysics Data System (ADS)

    Moran, E. H.; Lindsey, S.; van Breukelen, C. M.; Thoman, R.

    2016-12-01

    Spring Breakup on the large interior rivers in Alaska means a time of nervous anticipation for many of the residents in the villages alongside those rivers. On the Yukon and Kuskokwim Rivers the record flood for most villages occurred as a result of ice jams that backed up water and dump truck sized ice floes into the village. Those floods can occur suddenly and can literally wipe out a village. The challenge is that with a limited observation network (3 automated USGS gages along the 1200 miles of the Yukon River flowing through Alaska) and the inherently transient nature of ice jam formation, prediction of the timing and severity of these events has been a tremendous challenge. Staff at the Alaska Pacific River Forecast Center as well as the Alaska Region Climate Program Manager have been developing more quantitative tools to attempt to provide a longer lead time for villages to prepare for potentially devastating flooding. In the past, a very qualitative assessment of the primary drivers of Spring Breakup (snow pack, river ice thickness and forecast spring weather) have led to the successful identification of years when flood severity was likely to be elevated or significantly decreased. These qualitative assessments have also allowed the forecasting of the probability of either a thermal or a dynamic breakup. But there has continued to be a need for an objective tool that can handle weather patterns that border on the tails of the climatic distributions as well as the timing and flood potential from weather patterns that are closer to the median of the distribution. Over the past 8 years there have been a significant number of years with anomalous spring weather patterns including cold springs followed by rapid warmups leading to record flooding from ice jams during spring breakup (2009, 2013), record late breakup (2013), record early breakup (2016), record high snowfall (2012), record snowmelt and aufeis flooding (2015) and record low snowfall (2015). The need

  15. RESIDUAL MUTAGENICITY OF THE ALASKAN OIL SPILL ORGANICS

    EPA Science Inventory

    RESIDUAL MUTAGENICITY OF THE ALASKAN OIL SPILL ORGANICS. L.D.

    The Exxon Valdez, on March 24, 1989, spilled approximately eleven million gallons of Prudhoe Bay crude oil into the waters of Prince William Sound. Approximately 300 miles of
    contaminated beach are potential...

  16. Rural Alaskan Schools: Educational Specifications. Reprinted September, 1971.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Office of Public Information and Publications.

    The educational specifications of facilities for rural Alaskan schools are given in this 1964 report. Alaska's 6 recognized geographic regions are briefly described with consideration to topography, climate, permafrost conditions, latitude position, and transportation difficulties which present problems in planning schools. Since the school design…

  17. Curriculum Change and Self-Governing Agreements: A Yukon First Nation Case Study

    ERIC Educational Resources Information Center

    Lewthwaite, Brian Ellis; Owen, Thomas; Doiron, Ashley

    2015-01-01

    Recent developments in Canada's Yukon Territory draw attention to how political changes have potential for accelerating practices in education that are responsive to Indigenous Peoples' cultural knowledge systems and practices. In this study, through the use of case study methodology, an account of the changes that have occurred in one First…

  18. Leaf cuticular lipids on the Shandong and Yukon ecotypes of saltwater cress, eutrema salsugineum, and their response to water deficiency and impact on cuticle permeability

    USDA-ARS?s Scientific Manuscript database

    The impact of water deficit stress on leaf cuticular waxes and cutin monomers, and traits associated with cuticle permeability, were examined in Shandong and Yukon ecotypes of Eutrema salsugineum (syn. Thellungiella salsuginea). Although Shandong exhibits glaucous leaves, and Yukon is non-glaucous, ...

  19. Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yuan, Fengming; Yi, Shuhua; McGuire, A. David

    2012-01-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites andmore » evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ;0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2

  20. Timber resource statistics for the Upper Yukon inventory unit, Alaska, 1980.

    Treesearch

    Willem W.S. van Hees

    1987-01-01

    The 1980 inventory of the forest resources of the Upper Yukon unit was designed to produce inventory estimates of timberland area, volume of timber, and volumes of timber growth and mortality. Timberland area is estimated at 742,000 acres. Cubic-foot volume on all timberland is estimated at 475 million cubic feet. Timber growth and mortality are estimated at -615,000...

  1. Ordovician sponges from west-central and east-central Alaska and western Yukon Territory, Canada

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Britt, B.B.

    2008-01-01

    Moderate collections of fossil sponges have been recovered over a several-year period from a few scattered localities in west-central and east-central Alaska, and from westernmost Yukon Territory of Canada. Two fragments of the demosponge agelasiid cliefdenellid, Cliefdenella alaskaensis Stock, 1981, and mostly small unidentifiable additional fragments were recovered from a limestone debris flow bed in the White Mountain area, McGrath A-4 Quadrangle in west-central Alaska. Fragments of the agelasiid actinomorph girtyocoeliids Girtyocoeliana epiporata (Rigby & Potter, 1986) and Girtyocoelia minima n. sp., plus a specimen of the vaceletid colospongiid Corymbospongia amplia Rigby, Karl, Blodgett & Baichtal, 2005, were collected from probable Ashgillian age beds in the Livengood B-5 Quadrangle in east-central Alaska. A more extensive suite of corymbospongiids, including Corymbospongia betella Rigby, Potter & Blodgett, 1988, C. mica Rigby & Potter, 1986, and C.(?) perforata Rigby & Potter, 1986, along with the vaceletiid colospongiids Pseudo-imperatoria minima? (Rigby & Potter, 1986), and Pseudoimperatoria media (Rigby & Potter, 1986), and with the heteractinid Nucha naucum? Pickett & Jell, 1983, were recovered from uppermost part of the Jones Ridge Limestone (Ashgillian), on the south flank of Jones Ridge, in the Sheep Mountain Quadrangle, in westernmost Yukon Territory, Canada. The fossil sponges from the McGrath A-4 and Livengood B-5 quadrangles were recovered from attached Siberian terranes, and those from the Sheep Mountain Quadrangle were recovered from an allochthonous Laurentian terrane in the Yukon Territory.

  2. Alaskan Air Defense and Early Warning Systems Clear Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Alaskan Air Defense and Early Warning Systems - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  3. ERTS imagery applied to Alaskan coastal problems. [surface water circulation

    NASA Technical Reports Server (NTRS)

    Wright, F. F.; Sharma, G. D.; Burbank, D. C.; Burns, J. J.

    1974-01-01

    Along the Alaska coast, surface water circulation is relatively easy to study with ERTS imagery. Highly turbid river water, sea ice, and fluvial ice have proven to be excellent tracers of the surface waters. Sea truth studies in the Gulf of Alaska, Cook Inlet, Bristol Bay, and the Bering Strait area have established the reliability of these tracers. ERTS imagery in the MSS 4 and 5 bands is particularly useful for observing lower concentrations of suspended sediment, while MSS 6 data is best for the most concentrated plumes. Ice features are most clearly seen on MSS 7 imagery; fracture patterns and the movement of specific floes can be used to map circulation in the winter when runoff is restricted, if appropriate allowance is made for wind influence. Current patterns interpreted from satellite data are only two-dimensional, but since most biological activity and pollution are concentrated near the surface, the information developed can be of direct utility. Details of Alaska inshore circulation of importance to coastal engineering, navigation, pollution studies, and fisheries development have been clarified with satellite data. ERTS has made possible the analysis of circulation in many parts of the Alaskan coast.

  4. Geochemical evidence for the origin of late Quaternary loess in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.

    2006-01-01

    Loess is extensive in central Alaska, but there are uncertainties about its source and the direction of paleo-winds that deposited it. Both northerly and southerly winds have been inferred. The most likely sources of loess are the Tanana River (south), the Nenana River (southeast), and the Yukon River (north). Late Quaternary loess in central Alaska has immobile trace-element compositions (Cr/Sc, Th/Ta, Th/ Sc, Th/U, Eu/Eu*, GdN/YbN) that indicate derivation mostly from the Tanana River. However, other ratios (As/Sb, Zr/Hf, LaN/YbN) and quantitative modeling indicate that the Yukon River was also a source. During the last glacial period, there may have been a longer residence time of the Siberian and Canadian high-pressure cells, along with a strengthened Aleutian low-pressure cell. This would have generated regional-scale northeasterly winds and explains derivation of loess from the Yukon River. However, superim-posed upon this synoptic-scale circulation, there may have been strong, southerly katabatic winds from expanded glaciers on the northern flank of the Alaska Range. These winds could have provided eolian silt from the Tanana River. Yukon River and Tanana River sediments are highly calcareous, whereas Fairbanks-area loess is not. This suggests that carbonate leaching in loess kept ahead of sedimentation and that late Quaternary loess in central Alaska was deposited relatively slowly. ?? 2006 NRC Canada.

  5. Tackling “boundary faults” across the Alaska-Yukon border: a report from the field

    USGS Publications Warehouse

    Saltus, Rick

    2013-01-01

    One day in late May, a team of geologists from two countries and four different organizations got together in a remote corner of the Yukon Territory to try to rectify a mapping discrepancy called a “boundary fault.”

  6. Accumulated state assessment of the Yukon River watershed: part II quantitative effects-based analysis integrating Western science and traditional ecological knowledge.

    PubMed

    Dubé, Monique G; Wilson, Julie E; Waterhouse, Jon

    2013-07-01

    This article is the second in a 2-part series assessing the accumulated state of the transboundary Yukon River (YR) basin in northern Canada and the United States. The determination of accumulated state based on available long-term (LT) discharge and water quality data is the first step in watershed cumulative effect assessment in the absence of sufficient biological monitoring data. Long-term trends in water quantity and quality were determined and a benchmark against which to measure change was defined for 5 major reaches along the YR for nitrate, total and dissolved organic carbon (TOC and DOC, respectively), total phosphate (TP), orthophosphate, pH, and specific conductivity. Deviations from the reference condition were identified as "hot moments" in time, nested within a reach. Significant increasing LT trends in discharge were found on the Canadian portion of the YR. There were significant LT decreases in nitrate, TOC, and TP at the Headwater reach, and significant increases in nitrate and specific conductivity at the Lower reach. Deviations from reference condition were found in all water quality variables but most notably during the ice-free period of the YR (May-Sept) and in the Lower reach. The greatest magnitudes of outliers were found during the spring freshet. This study also incorporated traditional ecological knowledge (TEK) into its assessment of accumulated state. In the summer of 2007 the YR Inter Tribal Watershed Council organized a team of people to paddle down the length of the YR as part of a "Healing Journey," where both Western Science and TEK paradigms were used. Water quality data were continuously collected and stories were shared between the team and communities along the YR. Healing Journey data were compared to the LT reference conditions and showed the summer of 2007 was abnormal compared to the LT water quality. This study showed the importance of establishing a reference condition by reach and season for key indicators of water

  7. Arctic and subarctic environmental analyses utilizing ERTS-1 imagery. [permafrost sediment transport, snow cover, ice conditions, and water runoff in Alaska

    NASA Technical Reports Server (NTRS)

    Anderson, D. M.; Mckim, H. L.; Haugen, R. K.; Gatto, L. W.; Slaughter, C. W.; Marlar, T. L. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Physiognomic landscape features were used as geologic and vegetative indicators in preparation of a surficial geology, vegetation, and permafrost map at a scale of 1:1 million using ERTS-1 band 7 imagery. The detail from this map compared favorably with USGS maps at 1:250,000 scale. Physical boundaries mapped from ERTS-1 imagery in combination with ground truth obtained from existing small maps and other sources resulted in improved and more detailed maps of permafrost terrain and vegetation for the same area. ERTS-1 imagery provides for the first time, a means of monitoring the following regional estuarine processes: daily and periodic surface water circulation patterns; changes in the relative sediment load of rivers discharging into the inlet; and, several local patterns not recognized before, such as a clockwise back eddy offshore from Clam Gulch and a counterclockwise current north of the Forelands. Comparison of ERTS-1 and Mariner imagery has revealed that the thermokarst depressions found on the Alaskan North Slope and polygonal patterns on the Yukon River Delta are possible analogs to some Martian terrain features.

  8. Further contributions to the aleocharine fauna of the Yukon Territory, Canada (Coleoptera, Staphylinidae)

    PubMed Central

    Klimaszewski, Jan; Godin, Benoit; Bourdon, Caroline

    2012-01-01

    Abstract The aleocharine beetles of the Yukon Territory, Canada are reviewed based on material studied since the most recent survey of the territory in 2008. The present contribution recognizes a fauna of 125 species, of which 9 are new to science, 20 represent new territorial records and one represents a new Canadian record. Seventeen species are considered Holarctic, 6 introduced, and 2 species are of undetermined status (Holarctic or adventive). The Yukon fauna is classified in 32 genera and 8 tribes. The new species are: 1) Acrotona horwoodae Klimaszewski & Godin, sp. n.; 2) Atheta (Microdota) microelytrata Klimaszewski & Godin, sp. n.; 3) Atheta (Microdota) riparia Klimaszewski & Godin, sp. n.; 4) Atheta (Datomicra) whitehorsensis Klimaszewski & Godin, sp. n.; 5) Ocyusa yukonensis Klimaszewski & Godin, sp. n.; 6) Philhygra pseudolarsoniKlimaszewski & Godin, sp. n.; 7) Philhygra terrestris Klimaszewski & Godin, sp. n.; 8) Boreophilia davidgei Klimaszewski & Godin, sp. n.; and 9) Boreophilia herschelensis Klimaszewski & Godin, sp. n. PMID:22577321

  9. Effects of the Oil Spill on Alaskan Education.

    ERIC Educational Resources Information Center

    Oldaker, Lawrence Lee

    Oil-industry-produced revenues, help finance Alaskan state and local governmental services including education. Capital losses incurred by the Exxon Corporation and by commerical fisheries as a consequence of the Exxon Valdez oil spill caused an economic recession, the result being diminished financing for a number of governmental programs and…

  10. Sufentanil citrate immobilization of Alaskan moose calves.

    PubMed

    Kreeger, Terry J; Kellie, Kalin A

    2012-10-01

    Free-ranging Alaskan moose calves (Alces alces gigas) were immobilized with 0.12 mg/kg sufentanil (S; n=16), 0.12 mg/kg sufentanil plus 0.27 mg/kg xylazine (SX; n=11), or 0.007 mg/kg carfentanil plus 0.36 mg/kg xylazine (CX; n=13). Immobilants were antagonized with 1.2 mg/kg naltrexone (S) or 1.2 mg/kg naltrexone plus 2.4 mg/kg tolazoline (SX, CX). There were no differences in induction (P ≥ 0.29) or processing (P ≥ 0.44) times between groups. Moose given either S or SX had significantly shorter recovery times than moose given CX (P=0.001) and recovery times from S were shorter than from SX (P=0.02). Oxygen saturation values for all groups averaged 85 ± 8%, but were significantly higher (P=0.048) for CX (89 ± 7%) than for S (82 ± 8%). Based on these data, sufentanil at 0.1 mg/kg or sufentanil at 0.1 mg/kg plus xylazine at 0.25 mg/kg could provide effective remote immobilization for Alaskan moose calves and could be substituted for carfentanil or thiafentanil should the need arise.

  11. Migratory Patterns of Chinook Salmon Oncorhynchus tshawytscha Returning to a Large, Free-flowing River Basin

    USGS Publications Warehouse

    Eiler, John H.; Evans, Allison N.; Schreck, Carl B.

    2015-01-01

    Upriver movements were determined for Chinook salmon Oncorhynchus tshawytscha returning to the Yukon River, a large, virtually pristine river basin. These returns have declined dramatically since the late 1990s, and information is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio tagged during 2002–2004. Most (97.5%) of the fish tracked upriver to spawning areas displayed continual upriver movements and strong fidelity to the terminal tributaries entered. Movement rates were substantially slower for fish spawning in lower river tributaries (28–40 km d-1) compared to upper basin stocks (52–62 km d-1). Three distinct migratory patterns were observed, including a gradual decline, pronounced decline, and substantial increase in movement rate as the fish moved upriver. Stocks destined for the same region exhibited similar migratory patterns. Individual fish within a stock showed substantial variation, but tended to reflect the regional pattern. Differences between consistently faster and slower fish explained 74% of the within-stock variation, whereas relative shifts in sequential movement rates between “hares” (faster fish becoming slower) and “tortoises” (slow but steady fish) explained 22% of the variation. Pulses of fish moving upriver were not cohesive. Fish tagged over a 4-day period took 16 days to pass a site 872 km upriver. Movement rates were substantially faster and the percentage of atypical movements considerably less than reported in more southerly drainages, but may reflect the pristine conditions within the Yukon River, wild origins of the fish, and discrete run timing of the returns. Movement data can provide numerous insights into the status and management of salmon returns, particularly in large river drainages with widely scattered fisheries where management actions in the lower river potentially impact harvests and escapement farther upstream. However, the substantial variation

  12. New porcellioidean gastropods from early Devonian of Royal Creek area, Yukon Territory, Canada, with notes on their early phylogeny

    USGS Publications Warehouse

    Fryda, J.; Blodgett, R.B.; Lenz, A.C.; Manda, S.

    2008-01-01

    This paper presents a description of new gastropods belonging to the superfamily Porcellioidea (Vetigastropoda) from the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. This fauna belongs to Western Canada Province of the Old World Realm. The Pragian species Porcellia (Porcellia) yukonensis n. sp. and Porcellia (Paraporcellia) sp. represent the oldest presently known members of subgenera Porcellia (Porcellia) and Porcellia (Paraporcellia). Their simple shell ornamentation fits well with an earlier described evolutionary trend in shell morphology of the Porcellinae. Late Pragian to early Emsian Perryconcha pulchra n. gen. and n. sp. is the first member of the Porcellioidea bearing a row of tremata on adult teleoconch whorls. The occurrence of this shell feature in the Porcellioidea is additional evidence that the evolution of the apertural slit was much more complicated than has been proposed in classical models of Paleozoic gastropod evolution. Copyright ?? 2008, The Paleontological Society.

  13. Definition of Alaskan Aviation Training Requirements. Final Report.

    ERIC Educational Resources Information Center

    Mitchell, M. K.; And Others

    Because of high accident rates and the unique conditions faced in Arctic flying, a project was conducted to develop a training program for airline pilots flying over Alaska. Data were gathered, through the critical incident method in conjunction with traditional job-analysis procedures, about how experienced Alaskan pilots learned to cope with the…

  14. Needs Assessment for the Construction Industry in B.C. & the Yukon. Skill Plan.

    ERIC Educational Resources Information Center

    Lewe, Glenda

    A basic skills needs assessment developed a picture of the basic skills levels and needs of the construction industry in British Columbia and the Yukon. The three parts of the assessment were interviews with business managers and managers of other programs provided through joint labor/management initiatives, a questionnaire administered to…

  15. Carbon cycle uncertainty in the Alaskan Arctic

    NASA Astrophysics Data System (ADS)

    Fisher, J. B.; Sikka, M.; Oechel, W. C.; Huntzinger, D. N.; Melton, J. R.; Koven, C. D.; Ahlström, A.; Arain, A. M.; Baker, I.; Chen, J. M.; Ciais, P.; Davidson, C.; Dietze, M.; El-Masri, B.; Hayes, D.; Huntingford, C.; Jain, A.; Levy, P. E.; Lomas, M. R.; Poulter, B.; Price, D.; Sahoo, A. K.; Schaefer, K.; Tian, H.; Tomelleri, E.; Verbeeck, H.; Viovy, N.; Wania, R.; Zeng, N.; Miller, C. E.

    2014-02-01

    Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for Alaska, we provide a baseline of terrestrial carbon cycle structural and parametric uncertainty, defined as the multi-model standard deviation (σ) against the mean (x\\bar) for each quantity. Mean annual uncertainty (σ/x\\bar) was largest for net ecosystem exchange (NEE) (-0.01± 0.19 kg C m-2 yr-1), then net primary production (NPP) (0.14 ± 0.33 kg C m-2 yr-1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m-2 yr-1), gross primary production (GPP) (0.22 ± 0.50 kg C m-2 yr-1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m-2 yr-1), CH4 flux (2.52 ± 4.02 g CH4 m-2 yr-1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m-2 yr-1), and soil carbon (14.0± 9.2 kg C m-2). The spatial patterns in regional carbon stocks and fluxes varied widely with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Additionally, a feedback (i.e., sensitivity) analysis was conducted of 20th century NEE to CO2 fertilization (β) and climate (γ), which showed that uncertainty in γ was 2x larger than that of β, with neither indicating that the Alaskan Arctic is shifting towards a certain net carbon sink or source. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic.

  16. Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change.

    PubMed

    Yuan, F M; Yi, S H; McGuire, A D; Johnson, K D; Liang, J; Harden, J W; Kasischke, E S; Kurz, W A

    2012-12-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at -0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink

  17. Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change

    USGS Publications Warehouse

    Yuan, F.M.; Yi, S.H.; McGuire, A.D.; Johnson, K.D.; Liang, J.; Harden, J.W.; Kasischke, E.S.; Kurz, W.A.

    2012-01-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ∼0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink

  18. Integrating modelling and remote sensing to identify ecosystem performance anomalies in the boreal forest, Yukon River Basin, Alaska

    USGS Publications Warehouse

    Wylie, B.K.; Zhang, L.; Bliss, Norman B.; Ji, Lei; Tieszen, Larry L.; Jolly, W. M.

    2008-01-01

    High-latitude ecosystems are exposed to more pronounced warming effects than other parts of the globe. We develop a technique to monitor ecological changes in a way that distinguishes climate influences from disturbances. In this study, we account for climatic influences on Alaskan boreal forest performance with a data-driven model. We defined ecosystem performance anomalies (EPA) using the residuals of the model and made annual maps of EPA. Most areas (88%) did not have anomalous ecosystem performance for at least 6 of 8 years between 1996 and 2004. Areas with underperforming EPA (10%) often indicate areas associated with recent fires and areas of possible insect infestation or drying soil related to permafrost degradation. Overperforming areas (2%) occurred in older fire recovery areas where increased deciduous vegetation components are expected. The EPA measure was validated with composite burn index data and Landsat vegetation indices near and within burned areas.

  19. Characterization of Alaskan HMA mixtures with the simple performance tester.

    DOT National Transportation Integrated Search

    2014-05-01

    Material characterization provides basic and essential information for pavement design and the evaluation of hot mix asphalt (HMA). : This study focused on the accurate characterization of an Alaskan HMA mixture using an asphalt mixture performance t...

  20. Holocene Paleoceanographic Environments at the Chukchi-Alaskan Margin: Implications for Future Changes

    NASA Astrophysics Data System (ADS)

    Polyak, L.; Nam, S. I.; Dipre, G.; Kim, S. Y.; Ortiz, J. D.; Darby, D. A.

    2017-12-01

    The impacts of the North Pacific oceanic and atmospheric system on the Arctic Ocean result in accelerated sea-ice retreat and related changes in hydrography and biota in the western Arctic. Paleoclimatic records from the Pacific sector of the Arctic are key for understanding the long-term history of these interactions. As opposed to stratigraphically long but strongly compressed sediment cores recovered from the deep Arctic Ocean, sediment depocenters on the Chukchi-Alaskan margin yield continuous, medium to high resolution records formed since the last deglaciation. While early Holocene conditions were non-analogous to modern environments due to the effects of prolonged deglaciation and insufficiently high sea levels, mid to late Holocene sediments are more relevant for recent and modern climate variability. Notably, a large depocenter at the Alaskan margin has sedimentation rates estimated as high as a few millimeters per year, thus providing a decadal to near-annual resolution. This high accumulation can be explained by sediment delivery via the Alaskan Coastal Current originating from the Bering Sea and supposedly controlled by the Aleutian Low pressure center. Preliminary results from sediment cores recovering the last several centuries, along with a comparison with other paleoclimatic proxy records from the Arctic-North Pacific region, indicate a persistent role of the Aleutian Low in the Bering Strait inflow and attendant deposition. More proxy studies are underway to reconstruct the history of this circulation system and its relationship with sea ice extent. The expected results will improve our understanding of natural variability in oceanic and atmospheric conditions at the Chukchi-Alaskan margin, a critical area for modulating the Arctic climate change.

  1. Migratory Patterns of Wild Chinook Salmon Oncorhynchus tshawytscha Returning to a Large, Free-Flowing River Basin

    PubMed Central

    Eiler, John H.; Evans, Allison N.; Schreck, Carl B.

    2015-01-01

    Upriver movements were determined for Chinook salmon Oncorhynchus tshawytscha returning to the Yukon River, a large, virtually pristine river basin. These returns have declined dramatically since the late 1990s, and information is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio tagged during 2002–2004. Most (97.5%) of the fish tracked upriver to spawning areas displayed continual upriver movements and strong fidelity to the terminal tributaries entered. Movement rates were substantially slower for fish spawning in lower river tributaries (28–40 km d-1) compared to upper basin stocks (52–62 km d-1). Three distinct migratory patterns were observed, including a gradual decline, pronounced decline, and substantial increase in movement rate as the fish moved upriver. Stocks destined for the same region exhibited similar migratory patterns. Individual fish within a stock showed substantial variation, but tended to reflect the regional pattern. Differences between consistently faster and slower fish explained 74% of the within-stock variation, whereas relative shifts in sequential movement rates between “hares” (faster fish becoming slower) and “tortoises” (slow but steady fish) explained 22% of the variation. Pulses of fish moving upriver were not cohesive. Fish tagged over a 4-day period took 16 days to pass a site 872 km upriver. Movement rates were substantially faster and the percentage of atypical movements considerably less than reported in more southerly drainages, but may reflect the pristine conditions within the Yukon River, wild origins of the fish, and discrete run timing of the returns. Movement data can provide numerous insights into the status and management of salmon returns, particularly in large river drainages with widely scattered fisheries where management actions in the lower river potentially impact harvests and escapement farther upstream. However, the substantial variation

  2. Eastern Denali Fault surface trace map, eastern Alaska and Yukon, Canada

    USGS Publications Warehouse

    Bender, Adrian M.; Haeussler, Peter J.

    2017-05-04

    We map the 385-kilometer (km) long surface trace of the right-lateral, strike-slip Denali Fault between the Totschunda-Denali Fault intersection in Alaska, United States and the village of Haines Junction, Yukon, Canada. In Alaska, digital elevation models based on light detection and ranging and interferometric synthetic aperture radar data enabled our fault mapping at scales of 1:2,000 and 1:10,000, respectively. Lacking such resources in Yukon, we developed new structure-from-motion digital photogrammetry products from legacy aerial photos to map the fault surface trace at a scale of 1:10,000 east of the international border. The section of the fault that we map, referred to as the Eastern Denali Fault, did not rupture during the 2002 Denali Fault earthquake (moment magnitude 7.9). Seismologic, geodetic, and geomorphic evidence, along with a paleoseismic record of past ground-rupturing earthquakes, demonstrate Holocene and contemporary activity on the fault, however. This map of the Eastern Denali Fault surface trace complements other data sets by providing an openly accessible digital interpretation of the location, length, and continuity of the fault’s surface trace based on the accompanying digital topography dataset. Additionally, the digitized fault trace may provide geometric constraints useful for modeling earthquake scenarios and related seismic hazard.

  3. Denitrification and Nitrogen Fixation in Alaskan Continental Shelf Sediments

    PubMed Central

    Haines, John R.; Atlas, Ronald M.; Griffiths, Robert P.; Morita, Richard Y.

    1981-01-01

    Rates of nitrogen fixation and denitrification were measured in Alaskan continental shelf sediments. In some regions, rates of nitrogen fixation and denitrification appeared to be equal; in other areas, rates were significantly different. Potential rates of denitrification were found to be limited primarily by the available nitrate substrate. Major regional differences in rates of denitrification were not statistically significant, but significant differences were found for nitrogen fixation rates in different regions of the Alaskan continental shelf. Estimated net losses of nitrogen from Bering Sea sediments were calculated as 1.8 × 1012 g of N/yr. Experimental exposure of continental shelf sediments to petroleum hydrocarbons reduced rates of nitrogen fixation and denitrification in some cases but not others. Long-term exposure was necessary before a reduction in nitrogen fixation rates was observed; unamended rates of denitrification but not potential denitrification rates (NO3− added) were depressed after exposure to hydrocarbons. PMID:16345716

  4. Chemical Degradation of PCBs in Alaskan Soils

    DTIC Science & Technology

    2011-04-01

    problem was encountered by the Hawaii District (i.e., small volumes of PCB -contaminated soils at remote island sites). A previous study conducted by ERDC... Marshall . 2007. Simultaneous mobilization of heavy metals and polychlorinated biphenyl ( PCB ) compounds from soil with cyclodextrin and EDTA in...ER D C/ EL T R- 11 -3 Innovative Technology Advocate – Formerly Used Defense Sites Chemical Degradation of PCBs in Alaskan Soils En vi

  5. Viability of the Alaskan breeding population of Steller’s eiders

    USGS Publications Warehouse

    Dunham, Kylee; Grand, James B.

    2016-10-11

    The U.S. Fish and Wildlife Service is tasked with setting objective and measurable criteria for delisting species or populations listed under the Endangered Species Act. Determining the acceptable threshold for extinction risk for any species or population is a challenging task, particularly when facing marked uncertainty. The Alaskan breeding population of Steller’s eiders (Polysticta stelleri) was listed as threatened under the Endangered Species Act in 1997 because of a perceived decline in abundance throughout their nesting range and geographic isolation from the Russian breeding population. Previous genetic studies and modeling efforts, however, suggest that there may be dispersal from the Russian breeding population. Additionally, evidence exists of population level nonbreeding events. Research was conducted to estimate population viability of the Alaskan breeding population of Steller’s eiders, using both an open and closed model of population process for this threatened population. Projections under a closed population model suggest this population has a 100 percent probability of extinction within 42 years. Projections under an open population model suggest that with immigration there is no probability of permanent extinction. Because of random immigration process and nonbreeding behavior, however, it is likely that this population will continue to be present in low and highly variable numbers on the breeding grounds in Alaska. Monitoring the winter population, which includes both Russian and Alaskan breeding birds, may offer a more comprehensive indication of population viability.

  6. 33 CFR 334.1290 - In Bering Sea, Shemya Island Area, Alaska; meteorological rocket launching facility, Alaskan Air...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., Alaska; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. 334.1290 Section...; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. (a) The danger zone. An arc of a...) Rockets will normally be launched one each day Monday through Friday between 9 a.m. and 3 p.m. Rocket...

  7. 33 CFR 334.1290 - In Bering Sea, Shemya Island Area, Alaska; meteorological rocket launching facility, Alaskan Air...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Alaska; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. 334.1290 Section...; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. (a) The danger zone. An arc of a...) Rockets will normally be launched one each day Monday through Friday between 9 a.m. and 3 p.m. Rocket...

  8. 33 CFR 334.1290 - In Bering Sea, Shemya Island Area, Alaska; meteorological rocket launching facility, Alaskan Air...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., Alaska; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. 334.1290 Section...; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. (a) The danger zone. An arc of a...) Rockets will normally be launched one each day Monday through Friday between 9 a.m. and 3 p.m. Rocket...

  9. 33 CFR 334.1290 - In Bering Sea, Shemya Island Area, Alaska; meteorological rocket launching facility, Alaskan Air...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., Alaska; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. 334.1290 Section...; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. (a) The danger zone. An arc of a...) Rockets will normally be launched one each day Monday through Friday between 9 a.m. and 3 p.m. Rocket...

  10. 33 CFR 334.1290 - In Bering Sea, Shemya Island Area, Alaska; meteorological rocket launching facility, Alaskan Air...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., Alaska; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. 334.1290 Section...; meteorological rocket launching facility, Alaskan Air Command, U.S. Air Force. (a) The danger zone. An arc of a...) Rockets will normally be launched one each day Monday through Friday between 9 a.m. and 3 p.m. Rocket...

  11. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 4 2013-10-01 2013-10-01 false Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare..., developed in cooperation with the Yupi'k speaking population that resides in such communities, for...

  12. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 4 2014-10-01 2014-10-01 false Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare..., developed in cooperation with the Yupi'k speaking population that resides in such communities, for...

  13. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare..., developed in cooperation with the Yupi'k speaking population that resides in such communities, for...

  14. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare..., developed in cooperation with the Yupi'k speaking population that resides in such communities, for...

  15. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 4 2011-10-01 2011-10-01 false Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare..., developed in cooperation with the Yupi'k speaking population that resides in such communities, for...

  16. Major element concentrations in six Alaskan arctic rivers from melt to freeze-up

    NASA Astrophysics Data System (ADS)

    Douglas, T. A.; Barker, A.; Jacobson, A. D.; McClelland, J. W.; Khosh, M. S.; Lehn, G. O.

    2010-12-01

    It is increasingly evident that permafrost in the Arctic is responding to climate warming. An expected response to this warming is permafrost degradation and the downward migration of the seasonally thawed (active) layer into previously frozen material. This could allow weathering of previously frozen soils and influence surface water biogeochemistry in Arctic rivers. The weathering signal would most likely be evident in surface waters during summer and early fall base flow when the active layer is at its deepest extent. Studies collecting water samples from spring through late fall could capture these flows. Fieldwork in remote regions often requires long storage times for samples prior to analysis. One aspect of our study was to investigate whether waters collected for major element analyses should be preserved by acidification. We collected up to 60 surface water samples from each of six rivers between April and October, 2009. Two rivers were underlain by organic rich permafrost, two of the rivers drained mountainous bedrock, and two rivers were underlain by a combination of both bedrock and organic rich permafrost. We collected duplicate samples from each river. Samples were filtered in the field to less than 0.45 microns and collected into high density polyethylene bottles. Waters were stored for six months prior to analysis. One set of samples was analyzed without acidification while the second set was acidified with nitric acid to a pH of 2 after 6 months of storage. Concentrations of sodium, potassium, magnesium, calcium, ammonium, fluoride, chloride, nitrate, sulfate and phosphate were measured from all samples by ion chromatography. Sulfate, calcium, magnesium, sodium and potassium concentrations increase steadily through the summer from the end of spring melt into early fall. In all six rivers the potassium concentrations are unaffected by acidification. In the two streams underlain by organic rich permafrost and in one of the bedrock streams the calcium

  17. Impact of disability and other physical health issues on academic outcomes among American Indian and Alaskan Native college students: an exploratory analysis.

    PubMed

    Patterson Silver Wolf Adelv Unegv Waya, David A; Vanzile-Tamsen, Carol; Black, Jessica; Billiot, Shanondora M; Tovar, Molly

    2015-01-01

    This study investigated whether self-identified disabilities among American Indian and Alaskan Native college students impact academic performance and persistence to graduation and explored the differences in health and academic grades between American Indian and Alaskan Native students and students of other racial and ethnic identities using the National College Health Assessment. Findings indicate that American Indian or Alaskan Native students have significantly lower grades than White and Asian students, and American Indian and Alaskan Native women report the highest incidence of health problems of any demographic group. Exploratory results point to future research to determine the full impact of disabilities and poor health on academic success.

  18. The climate adaptation programs and activities of the Yellowstone to Yukon Conservation Initiative

    Treesearch

    Wendy L. Francis

    2011-01-01

    The Yellowstone to Yukon Conservation Initiative (Y2Y) is an innovative transboundary effort to protect biodiversity and facilitate climate adaptation by linking large protected core areas through compatible land uses on matrix lands. The Y2Y organization acts as the keeper of the Y2Y vision and implements two interconnected programs - Science and Action, and Vision...

  19. An Alaskan legend

    USGS Publications Warehouse

    Mann, H.; Blodgett, R.B.

    2009-01-01

    Jack Lee is a prominent personality, an Alaskan individualist and a skeptic worthy of remembrance if for no other reason than being inextricably associated with the catastrophic Katmai eruption in 1912. Jack remains a provocative reminder of Alaska's pre-1958 drilling and was quite possibly the earliest observer (excepting natives and possibly Russians) of the oil seeps in the area now encompassed by the Becharof National Wildlife Refuge. His observation of the impressive live oil seeps in the Ugashik and Becharof Lakes area, and his subsequent involvement in the early drilling entirely consumed his future interests. He is a firm believer that individualism and suspicion are powerful tools when forced to reconsider alternatives to readily accepted interpretations of modern exploration results. His individualism and sometimes annoying, but thought-provoking skepticism remains useful in any field where clich??s provide safe guards from new concepts.

  20. Overview of environmental and hydrogeologic conditions at Tanana, Alaska

    USGS Publications Warehouse

    Nakanishi, Allan S.; Dorava, Joseph M.

    1994-01-01

    The remote Native village of Tanana along the Yukon River in west-central Alaska has long cold winters and short summers. The Federal Aviation Administration owns or operates airway support facilities near Tanana and wishes to consider the subsistence lifestyle of the residents and the quality of the current environment when evaluating the severity of environmental contamination at these facilities. Tanana is located on the flood plain of the Yukon River and obtains its drinking water from a shallow aquifer located in thick alluvium underlying the village. Surface spills and disposal of hazardous materials combined with annual flooding of the Yukon River may affect the quality of the ground water. Alternative drinking-water sources are available, but may cost more than existing supplies.

  1. Multi-Scale Modeling of Boreal Forest Vegetation Growth Under the Influence of Permafrost and Wildfire Interactions

    NASA Astrophysics Data System (ADS)

    Foster, A.; Armstrong, A. H.; Shuman, J. K.; Ranson, K.; Shugart, H. H., Jr.; Rogers, B. M.; Goetz, S. J.

    2017-12-01

    Global temperatures have increased about 0.2°C per decade since 1979, and the high latitudes are warming faster than the rest of the globe. Climate change within Alaska is likely to bring about increased drought and longer fire seasons, as well as increases in the severity and frequency of fires. These changes in disturbance regimes and their associated effects on ecosystem C stocks, including permafrost, may lead to a positive feedback to further climate warming. As of now, it is uncertain how vegetation will respond to ongoing climate change, and the addition of disturbance effects leads to even more complicated and varied scenarios. Through ecological modeling, we have the capacity to examine forest processes at multiple temporal and spatial scales, allowing for the testing of complex interactions between vegetation, climate, and disturbances. The University of Virginia Forest Model Enhanced (UVAFME) is an individual tree-based forest model that has been updated for use in interior boreal Alaska, with a new permafrost model and updated fire simulation. These updated submodels allow for feedback between soils, vegetation, and fire severity through fuels tracking and impact of depth of burn on permafrost dynamics. We present these updated submodels as well as calibration and validation of UVAFME to the Yukon River Basin in Alaska, with comparisons to inventory data. We also present initial findings from simulations of potential future forest biomass, structure, and species composition across the Yukon River Basin under expected changes in precipitation, temperature, and disturbances. We predict changing climate and the associated impacts on wildfire and permafrost dynamics will result in shifts in biomass and species composition across the region, with potential for further feedback to the climate-vegetation-disturbance system. These simulations advance our understanding of the possible futures for the Alaskan boreal forest, which is a valuable part of the global

  2. Combining Ecosystem Observations, Manipulations and the Data Assimilation Research Testbed to Provide New Insights into Community Land Model Performance

    NASA Astrophysics Data System (ADS)

    Foster, A.; Armstrong, A. H.; Shuman, J. K.; Ranson, K.; Shugart, H. H., Jr.; Rogers, B. M.; Goetz, S. J.

    2016-12-01

    Global temperatures have increased about 0.2°C per decade since 1979, and the high latitudes are warming faster than the rest of the globe. Climate change within Alaska is likely to bring about increased drought and longer fire seasons, as well as increases in the severity and frequency of fires. These changes in disturbance regimes and their associated effects on ecosystem C stocks, including permafrost, may lead to a positive feedback to further climate warming. As of now, it is uncertain how vegetation will respond to ongoing climate change, and the addition of disturbance effects leads to even more complicated and varied scenarios. Through ecological modeling, we have the capacity to examine forest processes at multiple temporal and spatial scales, allowing for the testing of complex interactions between vegetation, climate, and disturbances. The University of Virginia Forest Model Enhanced (UVAFME) is an individual tree-based forest model that has been updated for use in interior boreal Alaska, with a new permafrost model and updated fire simulation. These updated submodels allow for feedback between soils, vegetation, and fire severity through fuels tracking and impact of depth of burn on permafrost dynamics. We present these updated submodels as well as calibration and validation of UVAFME to the Yukon River Basin in Alaska, with comparisons to inventory data. We also present initial findings from simulations of potential future forest biomass, structure, and species composition across the Yukon River Basin under expected changes in precipitation, temperature, and disturbances. We predict changing climate and the associated impacts on wildfire and permafrost dynamics will result in shifts in biomass and species composition across the region, with potential for further feedback to the climate-vegetation-disturbance system. These simulations advance our understanding of the possible futures for the Alaskan boreal forest, which is a valuable part of the global

  3. Differential declines in Alaskan boreal forest vitality related to climate and competition.

    PubMed

    Trugman, Anna T; Medvigy, David; Anderegg, William R L; Pacala, Stephen W

    2018-03-01

    Rapid warming and changes in water availability at high latitudes alter resource abundance, tree competition, and disturbance regimes. While these changes are expected to disrupt the functioning of boreal forests, their ultimate implications for forest composition are uncertain. In particular, recent site-level studies of the Alaskan boreal forest have reported both increases and decreases in productivity over the past few decades. Here, we test the idea that variations in Alaskan forest growth and mortality rates are contingent on species composition. Using forest inventory measurements and climate data from plots located throughout interior and south-central Alaska, we show significant growth and mortality responses associated with competition, midsummer vapor pressure deficit, and increased growing season length. The governing climate and competition processes differed substantially across species. Surprisingly, the most dramatic climate response occurred in the drought tolerant angiosperm species, trembling aspen, and linked high midsummer vapor pressure deficits to decreased growth and increased insect-related mortality. Given that species composition in the Alaskan and western Canadian boreal forests is projected to shift toward early-successional angiosperm species due to fire regime, these results underscore the potential for a reduction in boreal productivity stemming from increases in midsummer evaporative demand. © 2017 John Wiley & Sons Ltd.

  4. Outdoor recreation by Alaskans: projections for 2000 through 2020.

    Treesearch

    J. Michael. Bowker

    2001-01-01

    Outdoor recreation participation and consumption by Alaska residents are analyzed and projected to 2020. Both the rate of participation and the intensity of participation in nearly all outdoor recreation activities are higher among Alaskans than for residents of other states. Projections based on economic and demographic trends indicate that current patterns are likely...

  5. Sikuliqiruq: Ice dynamics of the Meade river - Arctic Alaska, from freezeup to breakup from time-series ground imagery

    USGS Publications Warehouse

    Beck, R.A.; Rettig, A.J.; Ivenso, C.; Eisner, Wendy R.; Hinkel, Kenneth M.; Jones, Benjamin M.; Arp, C.D.; Grosse, G.; Whiteman, D.

    2010-01-01

    Ice formation and breakup on Arctic rivers strongly influence river flow, sedimentation, river ecology, winter travel, and subsistence fishing and hunting by Alaskan Natives. We use time-series ground imagery ofthe Meade River to examine the process at high temporal and spatial resolution. Freezeup from complete liquid cover to complete ice cover ofthe Meade River at Atqasuk, Alaska in the fall of 2008 occurred in less than three days between 28 September and 2 October 2008. Breakup in 2009 occurred in less than two hours between 23:47 UTC on 23 May 2009 and 01:27 UTC on 24 May 2009. All times in UTC. Breakup in 2009 and 2010 was ofthe thermal style in contrast to the mechanical style observed in 1966 and is consistent with a warming Arctic. ?? 2010 Taylor & Francis.

  6. Leucocytozoon simondi in Emperor Geese from the Yukon-Kuskokwim Delta in Alaska

    USGS Publications Warehouse

    Hollmen, T.K.; Franson, J.C.; Creekmore, L.H.; Schmutz, J.A.; Fowler, A.C.

    1998-01-01

    We surveyed Emperor Geese (Chen canagica) in western Alaska for avian hematozoa. Blood smears were collected from 134 adults and goslings in late July 1996, on their breeding grounds on the Yukon-Kuskokwim Delta. One of 134 (0.7%) Emperor Geese harbored Leucocytozoon simondi, representing a new host record for this parasite. No other hematozoa were detected. This is one of few reports of avian blood parasites from the arctic tundra.

  7. Leucocytozoon simondi in emperor geese from the Yukon-Kuskokwim delta in Alaska

    USGS Publications Warehouse

    Hollmén, Tuula E.; Franson, J.C.; Creekmore, L.H.; Schmutz, J.A.; Fowler, A.C.

    1998-01-01

    We surveyed Emperor Geese (Chen canagica) in western Alaska for avian hematozoa. Blood smears were collected from 134 adults and goslings in late July 1996, on their breeding grounds on the Yukon-Kuskokwim Delta. One of 134 (0.7%) Emperor Geese harbored Leucocytozoon simondi, representing a new host record for this parasite. No other hematozoa were detected. This is one of few reports of avian blood parasites from the arctic tundra.

  8. Recent and Late Holocene Alaskan Lake Changes Identified from Water Isotopes

    NASA Astrophysics Data System (ADS)

    Anderson, L.; Birks, S. J.; Rover, J.; Guldager, N.

    2014-12-01

    To identify the existence and cause of recent lake area changes in the Yukon Flats, a region of discontinuous permafrost in north central Alaska, we evaluate lake water isotope compositions with remotely sensed imagery and hydroclimatic parameters. Estimates of the ratio of water lost by evaporation to that gained by inflow (E/I) were derived from an isotope-based water balance model. The isotope labels are also used to identify the dominant sources for lakes such as rainfall and snowfall, groundwater, rivers, or thawed permafrost. These parameters are then used in conjunction with climatic data and remotely sensed imagery to identify the patterns and causes of recent lake area changes and for evaluation with lake sediment oxygen isotope records of late Holocene lake water isotope variations. Lake water isotope samples from 83 lakes were acquired in July, August or September between 2007 and 2010 by fixed wing aircraft. An additional set of smaller lakes (n = 33) was sampled by helicopter in September 2009. In July 2011 59 lakes were sampled on foot within five distinct 11.2-km2 areas. River water data used here are previously collected during the months of June through October between 2006 and 2008. Isotope compositions indicate that mixtures of precipitation, river water, and groundwater source ~95% of the studied lakes. The remaining minority are more dominantly sourced by snowmelt and/or permafrost thaw. Isotope-based water balance estimates indicate 58% of lakes lose more than half of inflow by evaporation. For 26% of the lakes studied, evaporative losses exceeded supply. Surface area trend analysis indicates that most lakes were near their maximum extent in the early 1980s during a relatively cool and wet period. Subsequent reductions can be explained by moisture deficits and greater evaporation. Comparison with late Holocene isotope values and trends indicates recent changes are within the range of late Holocene variability. The records indicate a drier and

  9. Standard Implications: Alaskans Reflect on a Movement To Change Teaching.

    ERIC Educational Resources Information Center

    Calkins, Annie, Ed.; Christian, Scott, Ed.

    In this anthology, rural Alaskan English teachers in the Bread Loaf Rural Teacher Network describe their experiences implementing new state education standards while continuing their commitment to learner-centered and place-based practice. The book presents narratives about teaching grounded in knowledge and understanding of students and…

  10. Overview of environmental and hydrogeologic conditions at Galena, Alaska

    USGS Publications Warehouse

    Nakanishi, Allan S.; Dorava, Joseph M.

    1994-01-01

    The remote Native village of Galena along the Yukon River in west-central Alaska has long cold winters and short summers that affects the hydrology of the area. The Federal Aviation Administration owns or operates airport support facilities in Galena and wishes to consider the subsistence lifestyle of the residents and the quality of the current environment when evaluating options for remediation of environmental contamination at these facilities. Galena is located on the flood plain of the Yukon River and obtains its drinking water from a shallow aquifer located in the thick alluvium underlying the village. Surface spills and disposal of hazardous materials combined with annual flooding of the Yukon River may affect the quality of the ground water. Alternative drinking-water sources are available but at significantly greater cost than existing supplies.

  11. Village Science: A Resource Handbook for Rural Alaskan Teachers.

    ERIC Educational Resources Information Center

    Dick, Alan

    A resource handbook for rural Alaskan teachers covers village science, to make basic science concepts relevant to the physical environment in villages. Material is intended for use as filler for weeks that come up short on science materials, to provide stimulation for students who cannot see the relevance of science in their lives, and to help…

  12. Vitamin E status of Alaskan Eskimos.

    PubMed

    Wei Wo, C K; Draper, H H

    1975-08-01

    A survey was conducted during 1971-1973 on the vitamin E status of Alaskan Eskomos. The subjects were 315 residents of the northern coastal villages of Wainwright and Point Hope and the southwestern inland villages of Kasigluk and Nunapitchuk. Plasma vitamin E levels for the 6- to 17-year-old subjects at Wainwright, Point Hope, and Nunapitchuk were 0.81 plus or minus 0.26, 0.90 plus or minus 0.20, and 0.84 plus or minus 0.25 mg/100 ml (mean and standard deviation), respectively. The values for adults at Wainwright, Point Hope, and Kasigluk were 1.23 plus or minus 0.27, 1.23 plus or minus 0.27, and 1.27 plus or minus 0.33 mg/100 ml, respectively. No value less than 0.30 mg/100 ml was observed. Alpha-tocopherol was the only isomer present in significant amounts. Plasma vitamin E levels did not change significantly between 6 and 17 years of age; however, a steady increase with age was observed in the 18- to 69-year-old groups. Plasma alpha-tocopherol concentrations were significantly lower in children than in adults but there were no differences attributable to sex or geographic location. Vitamin E concentration in the blood plasma was linearly correlated with cholesterol concentration. Values are reported for the vitamin E content of some native foods. This study indicates that plasma vitamin E levels in Alaskan Eskimos consuming a high meat or fish diet are comparable to those in adults of the United States consuming a mixed diet.

  13. Nd isotopic characterization of metamorphic rocks in the Coast Mountains, Alaskan and Canadian Cordillera: Ancient crust bounded by juvenile terranes

    NASA Astrophysics Data System (ADS)

    Samson, Scott D.; Patchett, P. Jonathan; McClelland, William C.; Gehrels, George E.

    1991-08-01

    Nd isotopic data are reported for 52 samples from the crustal region between the Alexander-Wrangellia terrane and the Stikine terrane of the Alaskan and Canadian Cordillera. This region is composed of the Gravina belt, a Jurassic-Cretaceous assemblage of volcanic and clastic sedimentary rocks, the Taku terrane, a terrane of probable Early Permian to Late Triassic age, and four assemblages of metamorphic rocks that occur to the west of and within the Coast Mountains batholith. The Gravina belt has ɛNd(T) values that range from -1.1 to +8.3, similar to values of the underlying Alexander terrane, and consistent with the interpretation that it is a juvenile belt that formed in a back-arc or intra-arc basin within the Alexander terrane. Mid-Cretaceous plutons that were emplaced into the Gravina belt have ɛNd(T) values of +4.4 to +5.7 and were probably produced by mantle-derived melts that incorporated some Alexander terrane crust. The Taku terrane has ɛNd(0) values that range from -5.5 to +3.3, with corresponding depleted-mantle model (TDM) ages of 440 to 1430 Ma. A mid-Cretaceous pluton intruding the Taku terrane has an ɛNd(T) value of +5.1, a value indistinguishable from those determined for Cretaceous plutons intruding the Gravina belt. Metamorphic rocks east of and structurally overlying the Taku terrane are divided into the Tracy Arm assemblage, ɛNd(0)=-26 to 0, TDM=800-2450 Ma; the Endicott Arm assemblage, eNd(0)=-10 to -1.3, TDM=950-1500 Ma; the Port Houghton assemblage, ɛNd(0)=-9.4 to +1.1, TDM = 550-1500 Ma; and the Ruth assemblage, ɛNd(0) = -9.4 to +2.0, TDM=650-1300 Ma. These isotopic signatures indicate that a substantial component of each metamorphic assemblage was derived from Precambrian continental crust. The metamorphic rocks from these assemblages are lithologically very similar to rocks of the Yukon-Tanana (YTT) terrane of eastern Alaska and Yukon Territory and have such similar U-Pb detrital zircon ages and Nd isotopic compositions to YTT

  14. Clinical pathology and assessment of pathogen exposure in southern and Alaskan sea otters

    USGS Publications Warehouse

    Hanni, K.D.; Mazet, J.A.K.; Gulland, F.M.D.; Estes, James A.; Staedler, M.; Murray, M.J.; Miller, M.; Jessup, David A.

    2003-01-01

    The southern sea otter (Enhydra lutris nereis) population in California (USA) and the Alaskan sea otter (E. lutris kenyoni) population in the Aleutian Islands (USA) chain have recently declined. In order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 through 2000. Samples from 72 free-ranging Alaskan, 78 free-ranging southern, and (for pathogen exposure only) 41 debilitated southern sea otters in rehabilitation facilities were evaluated and compared to investigate regional differences. Serum chemistry and hematology values did not indicate a specific disease process as a cause for the declines. Statistically significant differences were found between free-ranging adult southern and Alaskan population mean serum levels of creatinine kinase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, calcium, cholesterol, creatinine, glucose, phosphorous, total bilirubin, blood urea nitrogen, and sodium. These were likely due to varying parasite loads, contaminant exposures, and physiologic or nutrition statuses. No free-ranging sea otters had signs of disease at capture, and prevalences of exposure to calicivirus, Brucella spp., and Leptospira spp. were low. The high prevalence (35%) of antibodies to Toxoplasma gondii in free-ranging southern sea otters, lack of antibodies to this parasite in Alaskan sea otters, and the pathogen's propensity to cause mortality in southern sea otters suggests that this parasite may be important to sea otter population dynamics in California but not in Alaska. The evidence for exposure to pathogens of public health importance (e.g., Leptospira spp., T. gondii) in the southern sea otter population, and the naïveté of both populations to other pathogens (e.g., morbillivirus

  15. Clinical pathology and assessment of pathogen exposure in southern and Alaskan sea otters.

    PubMed

    Hanni, Krista D; Mazet, Jonna A K; Gulland, Frances M D; Estes, James; Staedler, Michelle; Murray, Michael J; Miller, Melissa; Jessup, David A

    2003-10-01

    The southern sea otter (Enhydra lutris nereis) population in California (USA) and the Alaskan sea otter (E. lutris kenyoni) population in the Aleutian Islands (USA) chain have recently declined. In order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 through 2000. Samples from 72 free-ranging Alaskan, 78 free-ranging southern, and (for pathogen exposure only) 41 debilitated southern sea otters in rehabilitation facilities were evaluated and compared to investigate regional differences. Serum chemistry and hematology values did not indicate a specific disease process as a cause for the declines. Statistically significant differences were found between free-ranging adult southern and Alaskan population mean serum levels of creatinine kinase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, calcium, cholesterol, creatinine, glucose, phosphorous, total bilirubin, blood urea nitrogen, and sodium. These were likely due to varying parasite loads, contaminant exposures, and physiologic or nutrition statuses. No free-ranging sea otters had signs of disease at capture, and prevalences of exposure to calicivirus, Brucella spp., and Leptospira spp. were low. The high prevalence (35%) of antibodies to Toxoplasma gondii in free-ranging southern sea otters, lack of antibodies to this parasite in Alaskan sea otters, and the pathogen's propensity to cause mortality in southern sea otters suggests that this parasite may be important to sea otter population dynamics in California but not in Alaska. The evidence for exposure to pathogens of public health importance (e.g., Leptospira spp., T. gondii) in the southern sea otter population, and the naïveté of both populations to other pathogens (e.g., morbillivirus

  16. Geologic implications of topographic, gravity, and aeromagnetic data in the northern Yukon-Koyukuk Province and its borderlands, Alaska

    NASA Astrophysics Data System (ADS)

    Cady, John W.

    1989-11-01

    The northern Yukon-Koyukuk province is characterized by low elevation and high Bouguer gravity and aeromagnetic anomalies in contrast to the adjacent Brooks Range and Ruby geanticline. Using newly compiled digital topographic, gravity, and aeromagnetic maps, I have divided the province into three geophysical domains. The Koyukuk domain, which is nearly equivalent to the Koyukuk lithotectonic terrane, is a horseshoe-shaped area, open to the south, of low topography, high gravity, and high-amplitude magnetic anomalies caused by an intraoceanic magmatic arc. The Angayucham and Kanuti domains are geophysical subdivisions of the Angayucham lithotectonic terrane that occur along the northern and southeastern margins of the Yukon-Koyukuk province, where oceanic rocks have been thrust over continental rocks of the Brooks Range and Ruby geanticline. Basalt of the Angayucham domain causes strong gravity highs and weak magnetic highs. The Kanuti domain is distinguished from the Angayucham domain by intense magnetic highs caused by cumulus mafic and ultramafic plutonic rocks, abundant ultramafic mantle tectonites, and magnetic syenite and monzonite. Long-wavelength, low-intensity magnetic highs and undulating gravity anomalies indicate an undulating basement surface of varied lithology beneath the Kobuk-Koyukuk and Lower Yukon basins. Modeling of gravity and magnetic anomalies shows that oceanic rocks of the Angayucham and Kanuti domains dip inward beneath the Kobuk-Koyukuk basin. The modeling supports, but does not prove, the hypothesis that the crust of the Kobuk-Koyukuk basin is 32-35 km thick, consisting of a tectonically thickened section of Cretaceous volcanic and sedimentary rocks and older oceanic crust. Plutons of the Brooks Range and the southern Ruby geanticline are nonmagnetic, ilmenite series, S-type granites that cause magnetic lows. Plutons of the northern Ruby geanticline are variable in their magnetic properties and cause both highs and lows. Plutons of both

  17. Phlorotannins from Alaskan Seaweed Inhibit Carbolytic Enzyme Activity

    PubMed Central

    Kellogg, Joshua; Grace, Mary H.; Lila, Mary Ann

    2014-01-01

    Global incidence of type 2 diabetes has escalated over the past few decades, necessitating a continued search for natural sources of enzyme inhibitors to offset postprandial hyperglycemia. The objective of this study was to evaluate coastal Alaskan seaweed inhibition of α-glucosidase and α-amylase, two carbolytic enzymes involved in serum glucose regulation. Of the six species initially screened, the brown seaweeds Fucus distichus and Alaria marginata possessed the strongest inhibitory effects. F. distichus fractions were potent mixed-mode inhibitors of α-glucosidase and α-amylase, with IC50 values of 0.89 and 13.9 μg/mL, respectively; significantly more efficacious than the pharmaceutical acarbose (IC50 of 112.0 and 137.8 μg/mL, respectively). The activity of F. distichus fractions was associated with phlorotannin oligomers. Normal-phase liquid chromatography-mass spectrometry (NPLC-MS) was employed to characterize individual oligomers. Accurate masses and fragmentation patterns confirmed the presence of fucophloroethol structures with degrees of polymerization from 3 to 18 monomer units. These findings suggest that coastal Alaskan seaweeds are sources of α-glucosidase and α-amylase inhibitory phlorotannins, and thus have potential to limit the release of sugar from carbohydrates and thus alleviate postprandial hyperglycemia. PMID:25341030

  18. Rural Alaskan High School Boys' and Girls' Attitudes toward Education.

    ERIC Educational Resources Information Center

    Chu, Lily; Culbertson, Jeanne

    Questionnaires were administered to 73 sophomore and senior high school students in 3 isolated rural Alaska towns (Adak, Unalaska, and Dillingham) to study the effects of socio-economic factors on rural Alaskan youth's educational aspirations and expectations. Because of a military-supported economy, Adak was a typical middle class American…

  19. Circulation and water properties in the landfast ice zone of the Alaskan Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Weingartner, Thomas J.; Danielson, Seth L.; Potter, Rachel A.; Trefry, John H.; Mahoney, Andy; Savoie, Mark; Irvine, Cayman; Sousa, Leandra

    2017-09-01

    Moorings, hydrography, satellite-tracked drifters, and high-frequency radar data describe the annual cycle in circulation and water properties in the landfast ice zone (LIZ) of the Alaskan Beaufort Sea. Three seasons, whose duration and characteristics are controlled by landfast ice formation and ablation, define the LIZ: ;winter;, ;break-up;, and ;open-water;. Winter begins in October with ice formation and ends in June when rivers commence discharging. Winter LIZ ice velocities are zero, under-ice currents are weak ( 5 cm s-1), and poorly correlated with winds and local sea level. The along-shore momentum balance is between along-shore pressure gradients and bottom and ice-ocean friction. Currents at the landfast ice-edge are swift ( 35 cm s-1), wind-driven, with large horizontal shears, and potentially unstable. Weak cross-shore velocities ( 1 cm s-1) imply limited exchanges between the LIZ and the outer shelf in winter. The month-long break-up season (June) begins with the spring freshet and concludes when landfast ice detaches from the bottom. Cross-shore currents increase, and the LIZ hosts shallow ( 2 m), strongly-stratified, buoyant and sediment-laden, under-ice river plumes that overlie a sharp, 1 m thick, pycnocline across which salinity increases by 30. The plume salt balance is between entrainment and cross-shore advection. Break-up is followed by the 3-month long open-water season when currents are swift (≥20 cm s-1) and predominantly wind-driven. Winter water properties are initialized by fall advection and evolve slowly due to salt rejection from ice. Fall waters and ice within the LIZ derive from local rivers, the Mackenzie and/or Chukchi shelves, and the Arctic basin.

  20. Mesozoic thermal history and timing of structural events for the Yukon-Tanana Upland, east-central Alaska: 40Ar/39Ar data from metamorphic and plutonic rocks

    USGS Publications Warehouse

    Dusel-Bacon, C.; Lanphere, M.A.; Sharp, W.D.; Layer, P.W.; Hansen, V.L.

    2002-01-01

    We present new 40Ar/39Ar ages for hornblende, muscovite, and biotite from metamorphic and plutonic rocks from the Yukon-Tanana Upland, Alaska. Integration of our data with published 40Ar/39Ar, kinematic, and metamorphic pressure (P) and temperature (T) data confirms and refines the complex interaction of metamorphism and tectonism proposed for the region. The oldest metamorphic episode(s) postdates Middle Permian magmatism and predates the intrusion of Late Triassic (215-212 Ma) granitoids into the Fortymile River assemblage (Taylor Mountain assemblage of previous papers). In the eastern Eagle quadrangle, rapid and widespread Early Jurassic cooling is indicated by ???188-186 Ma 40Ar/39Ar plateau ages for hornblende from plutons that intrude the Fortymile River assemblage, and for metamorphic minerals from the Fortymile River assemblage and the structurally underlying Nasina assemblage. We interpret these Early Jurassic ages to represent cooling resulting from northwest-directed contraction that emplaced the Fortymile River assemblage onto the Nasina assemblage to the north as well as the Lake George assemblage to the south. This cooling was the final stage of a continuum of subduction-related contraction that produced crustal thickening, intermediate- to high-P metamorphism within both the Fortymile River assemblage and the structurally underlying Lake George assemblage, and Late Triassic and Early Jurassic plutonism in the Fortymile River and Nasina assemblages. Although a few metamorphic samples from the Lake George assemblage yield Jurassic 40Ar/39Ar cooling ages, most yield Early Cretaceous 40Ar/39Ar ages: hornblende ???135-115 Ma, and muscovite and biotite ???110-108 Ma. We interpret the Early Cretaceous metamorphic cooling, in most areas, to have resulted from regional extension and exhumation of the lower plate, previously tectonically thickened during Early Jurassic and older convergence.

  1. Paleoecological implications of Alaskan terrestrial vertebrate fauna in latest Cretaceous time at high paleolatitudes

    NASA Astrophysics Data System (ADS)

    Clemens, William A.; Gayle Nelms, L.

    1993-06-01

    The latest Cretaceous cool temperate environment of the Alaskan North Slope included dinosaurs (some species represented by both juveniles and adults) and mammals, all probably endothermic, and freshwater fish among its terrestrial vertebrate fauna. No traces have been found of amphibians or nondinosaurian reptiles, ectothermic vertebrates that are abundantly represented in approximately contemporaneous faunas of North American middle paleolatitudes. A geologically brief period of intense cold and darkness has been hypothesized as the primary cause of terminal Cretaceous extinctions. However, the extinction of the lineages of Alaskan dinosaurs and mammals, in contrast to the survival of most lineages of amphibians and nondinosaurian reptiles into the Tertiary, contradicts this hypothesis.

  2. EarthScope Transportable Array Siting Outreach Activities in Alaska and Western Canada

    NASA Astrophysics Data System (ADS)

    Dorr, P. M.; Gardine, L.; Tape, C.; McQuillan, P.; Cubley, J. F.; Samolczyk, M. A.; Taber, J.; West, M. E.; Busby, R.

    2015-12-01

    The EarthScope Transportable Array is deploying about 260 stations in Alaska and western Canada. IRIS and EarthScope are partnering with the Alaska Earthquake Center, part of the University of Alaska's Geophysical Institute, and Yukon College to spread awareness of earthquakes in Alaska and western Canada and the benefits of the Transportable Array for people living in these regions. We provide an update of ongoing education and outreach activities in Alaska and Canada as well as continued efforts to publicize the Transportable Array in the Lower 48. Nearly all parts of Alaska and portions of western Canada are tectonically active. The tectonic and seismic variability of Alaska, in particular, requires focused attention at the regional level, and the remoteness and inaccessibility of most Alaskan and western Canadian villages and towns often makes frequent visits difficult. When a community is accessible, every opportunity to engage the residents is made. Booths at state fairs and large cultural gatherings, such as the annual convention of the Alaska Federation of Natives, are excellent venues to distribute earthquake information and to demonstrate a wide variety of educational products and web-based applications related to seismology and the Transportable Array that residents can use in their own communities. Meetings and interviews with Alaska Native Elders and tribal councils discussing past earthquakes has led to a better understanding of how Alaskans view and understand earthquakes. Region-specific publications have been developed to tie in a sense of place for residents of Alaska and the Yukon. The Alaska content for IRIS's Active Earth Monitor emphasizes the widespread tectonic and seismic features and offers not just Alaska residents, but anyone interested in Alaska, a glimpse into what is going on beneath their feet. The concerted efforts of the outreach team will have lasting effects on Alaskan and Canadian understanding of the seismic hazard and

  3. ELECTRIC VEHICLE CONVERSIONS USING ALTERNATIVE ENERGY TO DRIVE ALASKAN RURAL COMMUNITIES

    EPA Science Inventory

    This proposal concerns sustainable transportation in rural Alaskan communities which are not part of a road or electrical network (off grid). In most off-grid communities, the road networks generally are less than 50 square miles, so transportation needs are limited. This limi...

  4. CYCLING OF DISSOLVED ELEMENTAL MERCURY IN ARCTIC ALASKAN LAKES. (R829796)

    EPA Science Inventory

    Aqueous production and water-air exchange of elemental mercury (Hg0) are important features of the environmental cycling of Hg. We investigated Hg0 cycling in ten Arctic Alaskan lakes that spanned a wide range in physicochemical characteristics. Dissolved...

  5. Alaska and Yukon magnetic compilation, residual total magnetic field

    USGS Publications Warehouse

    Miles, W.; Saltus, Richard W.; Hayward, N.; Oneschuk, D.

    2017-01-01

    This map is a compilation of aeromagnetic surveys over Yukon and eastern Alaska. Aeromagnetic surveys measure the total intensity of the earth's magnetic field. The field was measured by a magnetometer aboard an aircraft flown in parallel lines spaced at 200 m to 10000 m across the map area. The magnetic field reflects magnetic properties of bedrock and provides qualitative and quantitative information used in geological mapping. Understanding the geology will help geologists map the area, assist mineral/hydrocarbon exploration activities, and provide useful information necessary for communities, aboriginal associations, and government to make land use decisions. This survey was flown to improve our knowledge of the area. It will support ongoing geological mapping and resource assessment.

  6. Late nineteenth to early twenty-first century behavior of Alaskan glaciers as indicators of changing regional climate

    USGS Publications Warehouse

    Molnia, B.F.

    2007-01-01

    Alaska's climate is changing and one of the most significant indications of this change has been the late 19th to early 21st century behavior of Alaskan glaciers. Weather station temperature data document that air temperatures throughout Alaska have been increasing for many decades. Since the mid-20th century, the average change is an increase of ?????2.0????C. In order to determine the magnitude and pattern of response of glaciers to this regional climate change, a comprehensive analysis was made of the recent behavior of hundreds of glaciers located in the eleven Alaskan mountain ranges and three island areas that currently support glaciers. Data analyzed included maps, historical observations, thousands of ground-and-aerial photographs and satellite images, and vegetation proxy data. Results were synthesized to determine changes in length and area of individual glaciers. Alaskan ground photography dates from 1883, aerial photography dates from 1926, and satellite photography and imagery dates from the early 1960s. Unfortunately, very few Alaskan glaciers have any mass balance observations. In most areas analyzed, every glacier that descends below an elevation of ?????1500??m is currently thinning and/or retreating. Many glaciers have an uninterrupted history of continuous post-Little-Ice-Age retreat that spans more than 250??years. Others are characterized by multiple late 19th to early 21st century fluctuations. Today, retreating and/or thinning glaciers represent more than 98% of the glaciers examined. However, in the Coast Mountains, St. Elias Mountains, Chugach Mountains, and the Aleutian Range more than a dozen glaciers are currently advancing and thickening. Many currently advancing glaciers are or were formerly tidewater glaciers. Some of these glaciers have been expanding for more than two centuries. This presentation documents the post-Little-Ice-Age behavior and variability of the response of many Alaskan glaciers to changing regional climate. ?? 2006.

  7. 33 CFR 334.1300 - Blying Sound area, Gulf of Alaska, Alaska; air-to-air gunnery practice area, Alaskan Air Command...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., Alaska; air-to-air gunnery practice area, Alaskan Air Command, U.S. Air Force. 334.1300 Section 334.1300... gunnery practice area, Alaskan Air Command, U.S. Air Force. (a) The danger zone. A rhomboidal area... Air Command, U.S. Air Force, Anchorage, Alaska, or such agencies as he may designate. (Sec. 7, 40 Stat...

  8. 33 CFR 334.1300 - Blying Sound area, Gulf of Alaska, Alaska; air-to-air gunnery practice area, Alaskan Air Command...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Alaska; air-to-air gunnery practice area, Alaskan Air Command, U.S. Air Force. 334.1300 Section 334.1300... gunnery practice area, Alaskan Air Command, U.S. Air Force. (a) The danger zone. A rhomboidal area... Air Command, U.S. Air Force, Anchorage, Alaska, or such agencies as he may designate. (Sec. 7, 40 Stat...

  9. 33 CFR 334.1300 - Blying Sound area, Gulf of Alaska, Alaska; air-to-air gunnery practice area, Alaskan Air Command...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., Alaska; air-to-air gunnery practice area, Alaskan Air Command, U.S. Air Force. 334.1300 Section 334.1300... gunnery practice area, Alaskan Air Command, U.S. Air Force. (a) The danger zone. A rhomboidal area... Air Command, U.S. Air Force, Anchorage, Alaska, or such agencies as he may designate. (Sec. 7, 40 Stat...

  10. 33 CFR 334.1300 - Blying Sound area, Gulf of Alaska, Alaska; air-to-air gunnery practice area, Alaskan Air Command...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., Alaska; air-to-air gunnery practice area, Alaskan Air Command, U.S. Air Force. 334.1300 Section 334.1300... gunnery practice area, Alaskan Air Command, U.S. Air Force. (a) The danger zone. A rhomboidal area... Air Command, U.S. Air Force, Anchorage, Alaska, or such agencies as he may designate. (Sec. 7, 40 Stat...

  11. 33 CFR 334.1300 - Blying Sound area, Gulf of Alaska, Alaska; air-to-air gunnery practice area, Alaskan Air Command...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., Alaska; air-to-air gunnery practice area, Alaskan Air Command, U.S. Air Force. 334.1300 Section 334.1300... gunnery practice area, Alaskan Air Command, U.S. Air Force. (a) The danger zone. A rhomboidal area... Air Command, U.S. Air Force, Anchorage, Alaska, or such agencies as he may designate. (Sec. 7, 40 Stat...

  12. Fire history and fire management implications in the Yukon Flats National Wildlife Refuge, interior Alaska

    Treesearch

    S. A. Drury; P. J. Grissom

    2008-01-01

    We conducted this investigation in response to criticisms that the current Alaska Interagency Fire Management Plans are allowing too much of the landscape in interior Alaska to burn annually. To address this issue, we analyzed fire history patterns within the Yukon Flats National Wildlife Refuge, interior Alaska. We dated 40 fires on 27 landscape points within the...

  13. Rhenium and osmium isotopes in black shales and Ni-Mo-PGE-rich sulfide layers, Yukon Territory, Canada, and Hunan and Guizhou provinces, China

    USGS Publications Warehouse

    Horan, M.F.; Morgan, J.W.; Grauch, R.I.; Coveney, R.M.; Murowchick, J.B.; Hulbert, L.J.

    1994-01-01

    Rhenium and osmium abundances and osmium isotopic compositions were determined by negative thermal ionization mass spectrometry for samples of Devonian black shale and an associated Ni-enriched sulfide layer from the Yukon Territory, Canada. The same composition information was also obtained for samples of early Cambrian Ni-Mo-rich sulfide layers hosted in black shale in Guizhou and Hunan provinces, China. This study was undertaken to constrain the origin of the PGE enrichment in the sulfide layers. Samples of the Ni sulfide layer from the Yukon Territory are highly enriched in Re, Os, and other PGE, with distinctly higher Re/192Os but similar Pt/Re, compared to the black shale host. Re-Os isotopic data of the black shale and the sulfide layer are approximately isochronous, and the data plot close to reference isochrons which bracket the depositional age of the enclosing shales. Samples of the Chinese sulfide layers are also highly enriched in Re, Os, and the other PGE. Re/192Os are lower than in the Yukon sulfide layer. Re-Os isotopic data for the sulfide layers lie near a reference isochron with an age of 560 Ma, similar to the depositional age of the black shale host. The osmium isotopic data suggest that Re and PGE enrichment of the brecciated sulfide layers in both the Yukon Territory and in southern China may have occurred near the time of sediment deposition or during early diagenesis, during the middle to late Devonian and early Cambrian, respectively. ?? 1994.

  14. InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain

    USGS Publications Warehouse

    Rykhus, Russell P.; Lu, Zhong

    2008-01-01

    Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal Plain. To test our hypothesis that InSAR data are sufficiently sensitive to detect subsidence associated with thaw settlement, we acquired all Japanese Earth Resources Satellite-1 (JERS-1) L-band data available for the summers of 1996, 1997, and 1998 over two sites on the Alaska North Slope. The least amount of subsidence for both study sites was detected in the interferograms covering the summer of 1996 (2-3 cm), interferograms from 1997 and 1998 revealed that about 3 cm of subsidence occurred at the northern Cache One Lake site, and about 5 cm of subsidence was detected at the southern Kaparuk River site. These preliminary results illustrate the capacity of the L-band (24 cm) wavelength JERS-1 radar data to penetrate the short Arctic vegetation to monitor subsidence possibly associated with thaw settlement of the active layer and (or) other hydrologic changes over relatively large areas.

  15. Developing Aesthetically Compelling Visualizations for Documenting and Communicating Alaskan Glacier and Landscape Change

    NASA Astrophysics Data System (ADS)

    Molnia, B. F.

    2016-12-01

    For 50 years I have investigated glacier dynamics and attempted to convey this information to others. Since 2000, my focus has been on capturing and documenting decadal and century-scale Alaskan glacier and landscape change using precision repeat photography and on broadly communicate these results through simple, aesthetically compelling, unambiguous visualizations. As a young geologist, I spent the summer of 1968 on the Juneau Icefield, photographing its surface features and margins. Since then, I have taken 150,000 photographs of Alaskan glaciers and collected 5,000 historical Alaskan photographs taken by other, the earliest dating back to 1883. This database and my passion for photographing glaciers became the basis for an on-going investigation aimed at visually documenting glacier and landscapes change at more than 200 previously photographed Alaskan locations in Glacier Bay and Kenai Fjords National Parks, Prince William Sound, and the Coast Mountains. Repeat photography is a technique in which a historical and a modern photograph, both having similar fields of view, are compared and contrasted to quantitatively and qualitatively determine their similarities and differences. In precision repeat photography, both photographs have the same field of view, ideally being photographed from the identical location. Since 2000, I have conducted nearly 20 field campaigns to systematically revisit and re-photograph more than 225 fields of view previously captured in the historical photographs. As aesthetics are important in successfully communicating what has changed, substantial time and effort is invested in capturing new, comparable, generally cloud free photographs at each revisited site. The resulting modern images are then paired with similar field-of-view historical images to produce compelling, aesthetic photo pairs which depict long-term glacier, landscape, and ecosystem changes. As a few sites have multiple historical images, photo triplets or quadruplets are

  16. First nearctic records for Orius (Dimorphella) sibiricus Wagner (Hemiptera: Heteroptera: Anthocoridae), a Eurasian steppe inhabitant

    USDA-ARS?s Scientific Manuscript database

    Orius sibiricus Wagner, a dark-colored minute pirate bug widespread in the Eurasian Steppe, is recorded from sites near the Yukon River in Yukon, Canada. This species is distinguished from the melanic phenotype of Orius diespeter Herring by the more deeply and uniformly punctured dorsum, the subangu...

  17. Geologic Map of the Nulato Quadrangle, West-Central Alaska

    USGS Publications Warehouse

    Patton, W.W.; Moll-Stalcup, E. J.

    2000-01-01

    Introduction The Nulato quadrangle encompasses approximately 17,000 km2 (6,500 mi2) of west-central Alaska within the Yukon River drainage basin. The quadrangle straddles two major geologic features-the Yukon-Koyukuk sedimentary basin, a huge triangle-shaped Cretaceous depression that stretches across western Alaska from the Brooks Range to the Yukon delta; and the Ruby geanticline,a broad uplift of pre-Cretaceous rocks that borders the Yukon-Koyukuk basin on the southeast. The Kaltag Fault crosses the quadrangle diagonally from northeast to southwest and dextrally offsets all major geologic features as much as 130 km.

  18. Changes in Terrestrial Organic Carbon Delivery to the Colville River Delta and Adjacent Simpson's Lagoon Over the Late Holocene

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Bianchi, T. S.; Allison, M. A.; Miller, A. J.; Marcantonio, F.

    2012-04-01

    The Colville River in Alaska is the largest river in North America that drains only continuously permafrosted tundra, and as such provides a unique signal of historical changes in one of the world's most vulnerable areas to climate changes. Additionally, the Colville flows into Simpson's Lagoon, a shallow area of the Alaskan Beaufort coast protected by a barrier island chain, lessening the impacts of Arctic storms and ice grounding on sediment mixing. Cores collected from the Colville river delta in August of 2010 were found to be composed of muddy, organic-rich, well-laminated sediments. The 2.5 to 3 meter length of each core spans about one to two thousand years of Holocene history, including the entire Anthropocene and much of the late Holocene. Three cores were sampled for this data set, arranged latitudinally from the mouth of the Colville River east into Simpson's Lagoon. Samples were taken every 2 cm for the entire length of all cores. Bulk analyses including percent organic carbon, percent nitrogen, and stable carbon isotopic analysis were performed, and compound specific analyses including lignin-phenol and algal pigment analyses were performed. These analyses showed significant changes in carbon storage over the past one to two thousand years. There were also significant spatial differences in organic carbon inputs across the ~20km distance between the Colville mouth and the easternmost core. Lignin-phenol concentrations in surface sediments nearest to the river mouth correlated positively with reconstructed Alaskan North Slope temperatures, suggesting more terrestrial organic matter was delivered during higher temperature regimes. Molar C:N ratios and plant pigments correlated negatively and positively, respectively, with reconstructed Alaskan North Slope moisture regime, indicating greater algal inputs during wetter time periods. These data may in part be consistent with observed woody shrub encroachment and increasing expanse of permafrost lakes on the

  19. Incidence of adverse cardiac events 5 years after polymer-free sirolimus eluting stent implantation: Results from the prospective Bad Berka Yukon Choice™ registry.

    PubMed

    Ohlow, Marc-Alexander; von Korn, Hubertus; Gunkel, Oliver; Farah, Ahmed; Fuhrmann, Joerg T; Lauer, Bernward

    2014-12-01

    Drug-eluting stents (DES) constitute a major achievement in preventing re-stenosis, concerns remain regarding the increased inflammatory responses associated with the polymers used. This analysis focuses on outcomes in patients receiving the polymer-free sirolimus-eluting stent system YUKON-Choice (Yukon-DES, Translumina, Germany). From 01/2006-09/2008 all patients receiving Yukon-DES (≥2.5 mm diameter) were prospectively enrolled in our registry. The primary endpoint was long-term major adverse cardiac events (MACE). 701 patients were included in our registry. Mean age was 65.7 ± 10 years (73% male gender, 35.5% diabetes, and 32.2% acute coronary syndrome). 76% of the lesions were of Type B2/C. Lesion length was 24.6 ± 5.2 mm and mean stent diameter was 2.8 ± 0.4 mm. A total of 511 pts (72%) underwent 6-months angiographic follow-up, target vessel revascularization was noted in 23.5%. At 5 years clinical outcomes were: cardiac death 5.8%; myocardial infarction 3.4%; and TVR 24.6%. The incidence of MACE differed significantly between "on-label" and "off-label" indications (14.8% vs. 40.8% MACE; P < 0.001). Incidence of definitive/probable stent thrombosis (ST) was 1.14% (8/701); very late (>1 year) ST occurred in 0.29%. Our data suggests that the implantation of the sirolimus-coated polymer-free YUKON-DES is safe and feasible with a very low incidence of ST in this real world patient cohort with high percentage of diabetes and small vessels. © 2013 Wiley Periodicals, Inc.

  20. Water-quality data from lakes in the Yukon Flats, Alaska, 2010-2011

    USGS Publications Warehouse

    Halm, Douglas R.; Griffith, Brad

    2014-01-01

    Over a two-year period (2010–2011), in-place measurements were made and water-quality samples were collected from 122 lakes in the Yukon Flats, Alaska, during a U.S. Geological Survey lake biological diversity inventory. The U.S. Geological Survey National Research Program performed the chemical analyses on the retrieved water-quality samples. Results from the analyses of water samples for dissolved carbon gases and carbon isotopes, hydrogen and oxygen stable isotopes, dissolved organic carbon, and major cations and anions, along with supporting site data, are presented in this report.

  1. A Gly98Val Mutation in the N-Myc Downstream Regulated Gene 1 (NDRG1) in Alaskan Malamutes with Polyneuropathy

    PubMed Central

    Bruun, Camilla S.; Jäderlund, Karin H.; Berendt, Mette; Jensen, Kristine B.; Spodsberg, Eva H.; Gredal, Hanne; Shelton, G. Diane; Mickelson, James R.; Minor, Katie M.; Lohi, Hannes; Bjerkås, Inge; Stigen, Øyvind; Espenes, Arild; Rohdin, Cecilia; Edlund, Rebecca; Ohlsson, Jennie; Cizinauskas, Sigitas; Leifsson, Páll S.; Drögemüller, Cord; Moe, Lars; Cirera, Susanna; Fredholm, Merete

    2013-01-01

    The first cases of early-onset progressive polyneuropathy appeared in the Alaskan Malamute population in Norway in the late 1970s. Affected dogs were of both sexes and were ambulatory paraparetic, progressing to non-ambulatory tetraparesis. On neurologic examination, affected dogs displayed predominantly laryngeal paresis, decreased postural reactions, decreased spinal reflexes and muscle atrophy. The disease was considered eradicated through breeding programmes but recently new cases have occurred in the Nordic countries and the USA. The N-myc downstream-regulated gene (NDRG1) is implicated in neuropathies with comparable symptoms or clinical signs both in humans and in Greyhound dogs. This gene was therefore considered a candidate gene for the polyneuropathy in Alaskan Malamutes. The coding sequence of the NDRG1 gene derived from one healthy and one affected Alaskan Malamute revealed a non-synonymous G>T mutation in exon 4 in the affected dog that causes a Gly98Val amino acid substitution. This substitution was categorized to be “probably damaging” to the protein function by PolyPhen2 (score: 1.000). Subsequently, 102 Alaskan Malamutes from the Nordic countries and the USA known to be either affected (n = 22), obligate carriers (n = 7) or healthy (n = 73) were genotyped for the SNP using TaqMan. All affected dogs had the T/T genotype, the obligate carriers had the G/T genotype and the healthy dogs had the G/G genotype except for 13 who had the G/T genotype. A protein alignment showed that residue 98 is conserved in mammals and also that the entire NDRG1 protein is highly conserved (94.7%) in mammals. We conclude that the G>T substitution is most likely the mutation that causes polyneuropathy in Alaskan Malamutes. Our characterization of a novel candidate causative mutation for polyneuropathy offers a new canine model that can provide further insight into pathobiology and therapy of human polyneuropathy. Furthermore, selection against this mutation

  2. An assessment of educational needs in the Alaskan forest products industry.

    Treesearch

    Jon Thomas; Eric Hansen; Allen M. Brackley

    2005-01-01

    Major changes in federal forest policy in Alaska have resulted in a dramatic downsizing of the state's forest industry. These changes have driven efforts for economic restructuring and improved support for Alaskan communities. The University of Alaska Sitka Forest Products program at the University of Alaska Southeast is one example of efforts to better support...

  3. An assessment of educational needs in the Alaskan forest products industry

    Treesearch

    J. Thomas; E. Hansen; A. Brackley

    2005-01-01

    Major changes in federal forest policy in Alaska have resulted in a dramatic downsizing of the state's forest industry. These changes have driven efforts for economic restructuring and improved support for Alaskan communities. The University of Alaska Sitka Forest Products program at the University of Alaska Southeast is one example of efforts to better support...

  4. Shaping the Landscape: A Journal of Writing by Alaskan Teachers 1992.

    ERIC Educational Resources Information Center

    Longenbaugh, Betsy, Ed.

    Intended to encourage Alaska teachers to write, to provide an honest sounding board for those submitting work, and to be a pleasure to read, this booklet presents a collection of 20 pieces of writing (short stories, poems, and life experiences) by Alaskan teachers. The pieces and their authors are as follows: "The First Haiku" (Dan…

  5. Cultural Competency Perceptions: American Indian/Alaskan Native College Students and Academic Advisors

    ERIC Educational Resources Information Center

    Wesberry, Leslie C.

    2017-01-01

    This qualitative case study examined the perceptions of American Indian/Alaskan Native (AI/AN) undergraduate students. Specifically, the study researched if AI/AN college students attending Southeastern Oklahoma State University (SOSU) perceived academic advising as more useful if they were engaged by culturally competent academic advisors as…

  6. Black-flies and Leucocytozoon spp. as causes of mortality in juvenile Great Horned Owls in the Yukon, Canada

    Treesearch

    D. Bruce Hunter; Christoph Rohner; Doug C. Currie

    1997-01-01

    Black fly feeding and infection with the blood parasite Leucocytozoon spp. caused mortality in juvenile Great Horned Owls (Bubo virginianus) in the Yukon, Canada during 1989-1990. The mortality occurred during a year of food shortage corresponding with the crash in snowshoe hare (Lepus americanus) populations. We...

  7. Geologic implications of topographic, gravity, and aeromagnetic data in the northern Yukon-Koyukuk province and its borderlands, Alaska

    USGS Publications Warehouse

    Cady, J.W.

    1989-01-01

    The northern Yukon-Koyukuk province is characterized by low elevation and high Bouguer gravity and aeromagnetic anomalies in contrast to the adjacent Brooks Range and Ruby geanticline. Using newly compiled digital topographic, gravity, and aeromagnetic maps, the province is divided into three geophysical domains. The Koyukuk domain, which is nearly equivalent to the Koyukuk lithotectonic terrane, is a horseshoe-shaped area, open to the south, of low topography, high gravity, and high-amplitude magnetic anomalies caused by an intraoceanic magmatic arc. The Angayucham and Kanuti domains are geophysical subdivisions of the Angayucham lithotectonic terrane that occur along the northern and southeastern margins of the Yukon-Koyukuk province, where oceanic rocks have been thrust over continental rocks of the Brooks Range and Ruby geanticline. The modeling supports, but does not prove, the hypothesis that the crust of the Kobuk-Koyukuk basin is 32-35 km thick, consisting of a tectonically thickened section of Cretaceous volcanic and sedimentary rocks and older oceanic crust. -from Author

  8. Radiometric age file for Alaska: A section in The United States Geological Survey in Alaska: Accomplishments during 1980

    USGS Publications Warehouse

    Shew, Nora B.; Wilson, Frederic H.

    1982-01-01

    The Alaska radiometric age file of the Branch of Alaskan Geology is a computer-based compilation of radiometric dates from the state of Alaska and the western parts of the Yukon Territory and British Columbia. More than 1800 age determinations from over 250 references have been entered in the file. References date back to 1958 and include both published and unpublished sources. The file is the outgrowth of an original radiometric age file compiled by Don Grybeck and students at the University of Alaska-Fairbanks (Turner and others, 1975).

  9. Alaskan permafrost groundwater storage changes derived from GRACE and ground measurements

    Treesearch

    Reginald R. Muskett; Vladimir E. Romanovsky

    2011-01-01

    The Arctic is in transition from climate-driven thawing of permafrost. We investigate satellite-derived water equivalent mass changes, snow water equivalent with in situ measurements of runoff and ground-survey derived geoid models from 1999 through 2009. The Alaskan Arctic coastal plain groundwater storage (including wetland bog, thaw pond and lake) is increasing by 1...

  10. Alaskan Native Games--A Cross-Cultural Addition to the Physical Education Curriculum.

    ERIC Educational Resources Information Center

    Frey, Richard D.; Allen, Mike

    1989-01-01

    Importing traditional, yet unknown, physical activities from different cultures is an exciting way to add creativity and imagination to the physical education curriculum. Explanations, accompanied by teaching hints, are given of several traditional Alaskan native games which have been successfully used with K-Six students in the Anchorage School…

  11. Apatite fission-track evidence of widespread Eocene heating and exhumation in the Yukon-Tanana Upland, interior Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Murphy, J.M.

    2001-01-01

    We present an apatite fission-track (AFT) study of five plutonic rocks and seven metamorphic rocks across 310 km of the Yukon-Tanana Upland in east-central Alaska. Samples yielding ???40 Ma AFT ages and mean confined track lengths > 14 ??m with low standard deviations cooled rapidly from >120??C to 40 Ma suggest partial annealing and, therefore, lower maximum temperatures (???90-105??C). A few samples with single-grain ages of ???20 Ma apparently remained above ???50??C after initial cooling. Although the present geothermal gradient in the western Yukon-Tanana Upland is ???32??C/km, it could have been as high as 45??C/km during a widespread Eocene intraplate magmatic episode. Prior to rapid exhumation, samples with ???40 Ma AFT ages were >3.8-2.7 km deep and samples with >50 Ma AFT ages were >3.3-2.0 km deep. We calculate a 440-320 m/Ma minimum rate for exhumation of all samples during rapid cooling. Our AFT data, and data from rocks north of Fairbanks and from the Eielson deep test hole, indicate up to 3 km of post-40 Ma vertical displacement along known and inferred northeast-trending high-angle faults. The predominance of 40-50 Ma AFT ages throughout the Yukon-Tanana Upland indicates that, prior to the post-40 Ma relative uplift along some northeast-trending faults, rapid regional cooling and exhumation closely followed the Eocene extensional magmatism. We propose that Eocene magmatism and exhumation were somehow related to plate movements that produced regional-scale oroclinal rotation, northward translation of outboard terranes, major dextral strike-slip faulting, and subduction of an oceanic spreading ridge along the southern margin of Alaska.

  12. Relative importance of different secondary successional pathways in an Alaskan boreal forest

    Treesearch

    Thomas A. Kurkowski; Daniel H. Mann; T. Scott Rupp; David L. Verbyla

    2008-01-01

    Postfire succession in the Alaskan boreal forest follows several different pathways, the most common being self-replacement and species-dominance relay. In self-replacement, canopy-dominant tree species replace themselves as the postfire dominants. It implies a relatively unchanging forest composition through time maintained by trees segregated within their respective...

  13. Transport of Alaskan Dust into the Gulf of Alaska and Comparison with Similar High-Latitude Dust Environments

    NASA Technical Reports Server (NTRS)

    Crusium, John; Levy, Rob; Wang, Jun; Campbell, Rob; Schroth, Andrew W.

    2012-01-01

    Transport of Alaskan dust into the Gulf of Alaska and comparison with similar high-latitude dust environments. An airborne flux of the micronutrient iron, derived from dust originating from coastal regions may be an important contributor of iron to the Gulf of Alaska's (GoA) oligotrophic waters. Dust blowing off glacier termini and dry riverbeds is a recurring phenomenon in Alaska, usually occurring in the autumn. Since previous studies assumed that dust originating in the deserts of Asia was the largest source of . airborne iron to the GoA, the budget of aeolian deposition of iron needs to be reassessed. Since late 20 I 0, our group has been monitoring dust activity using satellites over the Copper River Delta (CRD) where the most vigorous dust plumes have been observed. Since 2011, sample aerosol concentration and their composition are being collected at Middleton Island (100km off shore of CRD). This presentation will show a summary of the ongoing dust observations and compare with other similar environments (Patagonia, Iceland) by showing case studies. Common features will be highlighted

  14. Earthquake triggering at alaskan volcanoes following the 3 November 2002 denali fault earthquake

    USGS Publications Warehouse

    Moran, S.C.; Power, J.A.; Stihler, S.D.; Sanchez, J.J.; Caplan-Auerbach, J.

    2004-01-01

    The 3 November 2002 Mw 7.9 Denali fault earthquake provided an excellent opportunity to investigate triggered earthquakes at Alaskan volcanoes. The Alaska Volcano Observatory operates short-period seismic networks on 24 historically active volcanoes in Alaska, 247-2159 km distant from the mainshock epicenter. We searched for evidence of triggered seismicity by examining the unfiltered waveforms for all stations in each volcano network for ???1 hr after the Mw 7.9 arrival time at each network and for significant increases in located earthquakes in the hours after the mainshock. We found compelling evidence for triggering only at the Katmai volcanic cluster (KVC, 720-755 km southwest of the epicenter), where small earthquakes with distinct P and 5 arrivals appeared within the mainshock coda at one station and a small increase in located earthquakes occurred for several hours after the mainshock. Peak dynamic stresses of ???0.1 MPa at Augustine Volcano (560 km southwest of the epicenter) are significantly lower than those recorded in Yellowstone and Utah (>3000 km southeast of the epicenter), suggesting that strong directivity effects were at least partly responsible for the lack of triggering at Alaskan volcanoes. We describe other incidents of earthquake-induced triggering in the KVC, and outline a qualitative magnitude/distance-dependent triggering threshold. We argue that triggering results from the perturbation of magmatic-hydrothermal systems in the KVC and suggest that the comparative lack of triggering at other Alaskan volcanoes could be a result of differences in the nature of magmatic-hydrothermal systems.

  15. Preliminary evidence for the involvement of budding bacteria in the origin of Alaskan placer gold

    USGS Publications Warehouse

    Watterson, J.R.

    1992-01-01

    Lacelike networks of micrometre-size filiform gold associated wtih Alaskan placer gold particles are interpreted as low-temperature pseudomorphs of a Pedomicrobium-like budding bacterium. Submicron reproductive structures (hyphae) and other morphological features similar to those of Pedomicrobium manganicum occur as detailed three-dimensional facsimiles in high purity gold in and on placer gold particles from Lillian Creek, Alaska. In a scanning electron microscope survey, the majority of gold particles at nine Alaskan placer deposits appear to include gold that has accumulated chemically at low temperatures in and on the cells of P. manganicum. Similar bacterioform gold from a Paleozoic deposit in China and from the Precambrian Witwatersrand deposit in South Africa may indicate that bacterioform gold is widespread. -Author

  16. Characterization of Alaskan hot-mix asphalt containing reclaimed asphalt pavement material : final report.

    DOT National Transportation Integrated Search

    2016-06-01

    In order to properly characterize Alaskan HMA materials containing RAP, this study evaluated properties of 3 asphalt binders typically : used in Alaska, PG 52-28, PG 52-40, and PG 58-34, and 11 HMA mixtures containing up to 35% RAP that were either p...

  17. Analysis of Alaskan burn severity patterns using remotely sensed data

    USGS Publications Warehouse

    Duffy, P.A.; Epting, J.; Graham, J.M.; Rupp, T.S.; McGuire, A.D.

    2007-01-01

    Wildland fire is the dominant large-scale disturbance mechanism in the Alaskan boreal forest, and it strongly influences forest structure and function. In this research, patterns of burn severity in the Alaskan boreal forest are characterised using 24 fires. First, the relationship between burn severity and area burned is quantified using a linear regression. Second, the spatial correlation of burn severity as a function of topography is modelled using a variogram analysis. Finally, the relationship between vegetation type and spatial patterns of burn severity is quantified using linear models where variograms account for spatial correlation. These results show that: 1) average burn severity increases with the natural logarithm of the area of the wildfire, 2) burn severity is more variable in topographically complex landscapes than in flat landscapes, and 3) there is a significant relationship between burn severity and vegetation type in flat landscapes but not in topographically complex landscapes. These results strengthen the argument that differential flammability of vegetation exists in some boreal landscapes of Alaska. Additionally, these results suggest that through feedbacks between vegetation and burn severity, the distribution of forest vegetation through time is likely more stable in flat terrain than it is in areas with more complex topography. ?? IAWF 2007.

  18. Semiautomatic mapping of permafrost in the Yukon Flats, Alaska

    NASA Astrophysics Data System (ADS)

    Gulbrandsen, Mats Lundh; Minsley, Burke J.; Ball, Lyndsay B.; Hansen, Thomas Mejer

    2016-12-01

    Thawing of permafrost due to global warming can have major impacts on hydrogeological processes, climate feedback, arctic ecology, and local environments. To understand these effects and processes, it is crucial to know the distribution of permafrost. In this study we exploit the fact that airborne electromagnetic (AEM) data are sensitive to the distribution of permafrost and demonstrate how the distribution of permafrost in the Yukon Flats, Alaska, is mapped in an efficient (semiautomatic) way, using a combination of supervised and unsupervised (machine) learning algorithms, i.e., Smart Interpretation and K-means clustering. Clustering is used to sort unfrozen and frozen regions, and Smart Interpretation is used to predict the depth of permafrost based on expert interpretations. This workflow allows, for the first time, a quantitative and objective approach to efficiently map permafrost based on large amounts of AEM data.

  19. Semiautomatic mapping of permafrost in the Yukon Flats, Alaska

    USGS Publications Warehouse

    Gulbrandsen, Mats Lundh; Minsley, Burke J.; Ball, Lyndsay B.; Hansen, Thomas Mejer

    2016-01-01

    Thawing of permafrost due to global warming can have major impacts on hydrogeological processes, climate feedback, arctic ecology, and local environments. To understand these effects and processes, it is crucial to know the distribution of permafrost. In this study we exploit the fact that airborne electromagnetic (AEM) data are sensitive to the distribution of permafrost and demonstrate how the distribution of permafrost in the Yukon Flats, Alaska, is mapped in an efficient (semiautomatic) way, using a combination of supervised and unsupervised (machine) learning algorithms, i.e., Smart Interpretation and K-means clustering. Clustering is used to sort unfrozen and frozen regions, and Smart Interpretation is used to predict the depth of permafrost based on expert interpretations. This workflow allows, for the first time, a quantitative and objective approach to efficiently map permafrost based on large amounts of AEM data.

  20. Repertoire and classification of non-song calls in Southeast Alaskan humpback whales (Megaptera novaeangliae).

    PubMed

    Fournet, Michelle E; Szabo, Andy; Mellinger, David K

    2015-01-01

    On low-latitude breeding grounds, humpback whales produce complex and highly stereotyped songs as well as a range of non-song sounds associated with breeding behaviors. While on their Southeast Alaskan foraging grounds, humpback whales produce a range of previously unclassified non-song vocalizations. This study investigates the vocal repertoire of Southeast Alaskan humpback whales from a sample of 299 non-song vocalizations collected over a 3-month period on foraging grounds in Frederick Sound, Southeast Alaska. Three classification systems were used, including aural spectrogram analysis, statistical cluster analysis, and discriminant function analysis, to describe and classify vocalizations. A hierarchical acoustic structure was identified; vocalizations were classified into 16 individual call types nested within four vocal classes. The combined classification method shows promise for identifying variability in call stereotypy between vocal groupings and is recommended for future classification of broad vocal repertoires.

  1. Stratigraphy and sedimentology of the Mid-Cretaceous deposits of the Yukon-Koyukuk Basin, west central Alaska

    NASA Astrophysics Data System (ADS)

    Nilsen, Tor H.

    1989-11-01

    The northeast trending Yukon-Koyukuk basin of west central Alaska consists of two subbasins, the Kobuk-Koyukuk subbasin to the north and east and the Lower Yukon subbasin to the southwest. The subbasins are separated by an arcuate Lower Cretaceous volcanic pile, the Hogatza trend, which is thought to be an accreted volcanic arc. The oldest part of the sedimentary fill of the subbasins consists of Valanginian to lower Albian(?) volcaniclastic rocks deposited on the flanks of the Hogatza trend. Following subsidence of the Hogatza trend, mid-Cretaceous clastic sedimentary strata of mainly Albian and Cenomanian age, and possibly as thick as 8000 m, were shed into the basin; these deposits were derived from surrounding uplands or borderlands in the Seward Peninsula to the west, the Brooks Range to the north, and the Ruby geanticline to the southeast. These mid-Cretaceous basin fill deposits can be divided into four main facies: (1) basin margin conglomerate facies, chiefly alluvial fan deposits that were transported basinward and rest in part unconformably on the surrounding uplands; (2) shelf facies, chiefly cross-stratified and hummocky cross-stratified sandstone deposited by wave-generated currents on a shelf that rimmed the basin on its western and northern margins; (3) deltaic facies, chiefly sandstone and shale deposited in delta plain and delta front environments on a large constructional delta that prograded westward from the eastern basin margin across both subbasins and across the subsided southern part of the Hogatza trend; and (4) turbidite facies, chiefly interbedded sandstone and shale deposited as elongate deep-sea fans and related deep-sea clastic systems by flows that transported sediment to the axial parts of both subbasins, northeastward in the Lower Yukon subbasin and eastward to southward in the Kobuk-Koyukuk subbasin. Sedimentation appears to have ended in the Santonian, followed by uplift, folding, and faulting of the basin fill. Less deformed

  2. Distribution, stock composition and timing, and tagging response of wild Chinook Salmon returning to a large, free-flowing river basin

    USGS Publications Warehouse

    Eiler, John H.; Masuda, Michele; Spencer, Ted R.; Driscoll, Richard J.; Schreck, Carl B.

    2014-01-01

    Chinook Salmon Oncorhynchus tshawytscha returns to the Yukon River basin have declined dramatically since the late 1990s, and detailed information on the spawning distribution, stock structure, and stock timing is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio-tagged in the lower basin during 2002–2004 and tracked upriver. Fish traveled to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging site. Similar distribution patterns were observed across years, suggesting that the major components of the run were identified. Daily and seasonal composition estimates were calculated for the component stocks. The run was dominated by two regional components comprising over 70% of the return. Substantially fewer fish returned to other areas, ranging from 2% to 9% of the return, but their collective contribution was appreciable. Most regional components consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that the differences in abundance were not related to regional or stock-specific variability. Run timing was relatively compressed compared with that in rivers in the southern portion of the species’ range. Most stocks passed through the lower river over a 6-week period, ranging in duration from 16 to 38 d. Run timing was similar for middle- and upper-basin stocks, limiting the use of timing information for management. The lower-basin stocks were primarily later-run fish. Although differences were observed, there was general agreement between our composition and timing estimates and those from other assessment projects within the basin, suggesting that the telemetry-based estimates provided a plausible approximation of the return. However, the short duration of the run, complex stock structure, and

  3. Alaska Is Our Home--Book 2: A Natural Science Handbook for Alaskan Students.

    ERIC Educational Resources Information Center

    Bury, John; Bury, Susan

    A natural science resource booklet for teachers and students contains detailed materials for teaching and learning about Alaskan wildlife. Each of nine chapters provides background subject information, suggested learning activities, tear-out pages of review questions for students to answer, and supplementary notes for teachers which include…

  4. Seasonal Storminess in the North Pacific, Bering Sea, and Alaskan Regions

    NASA Astrophysics Data System (ADS)

    Shippee, N. J.; Atkinson, D. E.; Walsh, J. E.; Partain, J.; Gottschalck, J.; Marra, J.

    2012-12-01

    Annually, extra-tropical cyclones present a high impact natural hazard to the North Pacific, Bering Sea, and Alaskan regions. In these regions, extensive subsistence and commercial fishing, new oil and gas field development, tourism, growing interest in and exploitation of new commercial shipping potential, and increasing military and Coast Guard activity, all represent potential parties impacted by storms in these waters. It is of interest to many parties to begin developing capacity to provide some indication of storm activity at a monthly- to seasonal-outlook (30 to 90 days) timeframe. Using storm track data from NOAA's Climate Prediction Center for the North Pacific and Alaskan region, an experimental seasonal storminess outlook product, using eigen-based methods similar to the operational seasonal temperature and precipitation products currently produced at NOAA CPC, has been created and tested in hindcast mode using predicted states of ENSO, the Pacific Decadal Oscillation (PDO), the Pacific-North American Pattern (PNA), and the Arctic Oscillation (AO). A sample of the seasonal storminess outlook product will be shown along with a discussion of the utility of individual teleconnection patterns in the generation of the product.

  5. NifH-Harboring Bacterial Community Composition across an Alaskan Permafrost Thaw Gradient

    PubMed Central

    Penton, C. Ryan; Yang, Caiyun; Wu, Liyou; Wang, Qiong; Zhang, Jin; Liu, Feifei; Qin, Yujia; Deng, Ye; Hemme, Christopher L.; Zheng, Tianling; Schuur, Edward A. G.; Tiedje, James; Zhou, Jizhong

    2016-01-01

    Since nitrogen (N) is often limiting in permafrost soils, we investigated the N2-fixing genetic potential and the inferred taxa harboring those genes by sequencing nifH gene fragments in samples taken along a permafrost thaw gradient in an Alaskan boreal soil. Samples from minimally, moderately and extensively thawed sites were taken to a depth of 79 cm to encompass zones above and below the depth of the water table. NifH reads were translated with frameshift correction and 112,476 sequences were clustered at 5% amino acid dissimilarity resulting in 1,631 OTUs. Sample depth in relation to water table depth was correlated to differences in the NifH sequence classes with those most closely related to group I nifH-harboring Alpha- and Beta-Proteobacteria in higher abundance above water table depth while those related to group III nifH-harboring Delta Proteobacteria more abundant below. The most dominant below water table depth NifH sequences, comprising 1/3 of the total, were distantly related to Verrucomicrobia-Opitutaceae. Overall, these results suggest that permafrost thaw alters the class-level composition of N2-fixing communities in the thawed soil layers and that this distinction corresponds to the depth of the water table. These nifH data were also compared to nifH sequences obtained from a study at an Alaskan taiga site, and to those of other geographically distant, non-permafrost sites. The two Alaska sites were differentiated largely by changes in relative abundances of the same OTUs, whereas the non-Alaska sites were differentiated by the lack of many Alaskan OTUs, and the presence of unique halophilic, sulfate- and iron-reducing taxa in the Alaska sites. PMID:27933054

  6. NifH-Harboring Bacterial Community Composition across an Alaskan Permafrost Thaw Gradient

    DOE PAGES

    Penton, C. Ryan; Yang, Caiyun; Wu, Liyou; ...

    2016-11-24

    Since nitrogen (N) is often limiting in permafrost soils, we investigated the N 2-fixing genetic potential and the inferred taxa harboring those genes by sequencing nifH gene fragments in samples taken along a permafrost thaw gradient in an Alaskan boreal soil. Samples from minimally, moderately and extensively thawed sites were taken to a depth of 79 cm to encompass zones above and below the depth of the water table. NifH reads were translated with frameshift correction and 112,476 sequences were clustered at 5% amino acid dissimilarity resulting in 1,631 OTUs. Sample depth in relation to water table depth was correlatedmore » to differences in the NifH sequence classes with those most closely related to group I nifH-harboring Alpha- and Beta-Proteobacteria in higher abundance above water table depth while those related to group III nifH-harboring Delta Proteobacteria more abundant below. The most dominant below water table depth NifH sequences, comprising 1/3 of the total, were distantly related to Verrucomicrobia-Opitutaceae. Overall, these results suggest that permafrost thaw alters the class-level composition of N 2-fixing communities in the thawed soil layers and that this distinction corresponds to the depth of the water table. These nifH data were also compared to nifH sequences obtained from a study at an Alaskan taiga site, and to those of other geographically distant, non-permafrost sites. The two Alaska sites were differentiated largely by changes in relative abundances of the same OTUs, whereas the non-Alaska sites were differentiated by the lack of many Alaskan OTUs, and the presence of unique halophilic, sulfate- and iron-reducing taxa in the Alaska sites.« less

  7. Levoglucosan Levels in Alaskan Ice Cores as a Record of Past Wildfires

    NASA Astrophysics Data System (ADS)

    Dunham, M. E.; Osterberg, E. C.; Kehrwald, N. M.; Kennedy, J.; Ferris, D. G.

    2017-12-01

    Glaciers in southeast Alaska are significant contributors to global sea-level rise, and therefore understanding the mechanisms driving their recent mass loss is crucial for predicting future sea-level change. Fire activity in Alaska has increased dramatically during the last decade, adding a potential new source of light-absorbing organic material (soot) to the Juneau Icefield that can reduce albedo and enhance surface melt rates. The goal of this project is to create an accurate record of Alaskan wildfires to understand how Alaskan glacial mass balance is affected by the deposition of organic aerosols from wildfires. Previously, oxalate, ammonia, and potassium ion levels have been used as proxies for past wildfire activity, but these ions all have broader emission sources in addition to wildfires. Here we develop a record of past Alaskan fire events and climate from: (1) levels of a biomass burning indicator, levoglucosan, which only forms when cellulose is burned over 300 °C, (2) major ions including oxalate, ammonia, and potassium; (3) the number and size distribution of particles to quantify trace amounts of soot from wildfires; and (4) stable water isotope ratios as a proxy for past temperature in ice cores. We utilize a total of four shallow ice cores, ranging from 7 to 9 m in length, that were collected by a biogeochemistry team during the Juneau Icefield Research Program (JIRP) in 2016. Complications include our limited understanding of the conservation and degradation of levoglucosan over time or during the firnification process. We hypothesize that particle counts will be correlated with levoglucosan peaks, co-varying with wildfire frequency and temperatures over time. Based on previous work, we also expect to find correlations between levoglucosan and oxalate ion concentrations, even though oxalate ions have sources in addition to wildfire activity.

  8. NifH-Harboring Bacterial Community Composition across an Alaskan Permafrost Thaw Gradient

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Penton, C. Ryan; Yang, Caiyun; Wu, Liyou

    Since nitrogen (N) is often limiting in permafrost soils, we investigated the N 2-fixing genetic potential and the inferred taxa harboring those genes by sequencing nifH gene fragments in samples taken along a permafrost thaw gradient in an Alaskan boreal soil. Samples from minimally, moderately and extensively thawed sites were taken to a depth of 79 cm to encompass zones above and below the depth of the water table. NifH reads were translated with frameshift correction and 112,476 sequences were clustered at 5% amino acid dissimilarity resulting in 1,631 OTUs. Sample depth in relation to water table depth was correlatedmore » to differences in the NifH sequence classes with those most closely related to group I nifH-harboring Alpha- and Beta-Proteobacteria in higher abundance above water table depth while those related to group III nifH-harboring Delta Proteobacteria more abundant below. The most dominant below water table depth NifH sequences, comprising 1/3 of the total, were distantly related to Verrucomicrobia-Opitutaceae. Overall, these results suggest that permafrost thaw alters the class-level composition of N 2-fixing communities in the thawed soil layers and that this distinction corresponds to the depth of the water table. These nifH data were also compared to nifH sequences obtained from a study at an Alaskan taiga site, and to those of other geographically distant, non-permafrost sites. The two Alaska sites were differentiated largely by changes in relative abundances of the same OTUs, whereas the non-Alaska sites were differentiated by the lack of many Alaskan OTUs, and the presence of unique halophilic, sulfate- and iron-reducing taxa in the Alaska sites.« less

  9. Prevalence of algal toxins in Alaskan marine mammals foraging in a changing arctic and subarctic environment.

    PubMed

    Lefebvre, Kathi A; Quakenbush, Lori; Frame, Elizabeth; Huntington, Kathy Burek; Sheffield, Gay; Stimmelmayr, Raphaela; Bryan, Anna; Kendrick, Preston; Ziel, Heather; Goldstein, Tracey; Snyder, Jonathan A; Gelatt, Tom; Gulland, Frances; Dickerson, Bobette; Gill, Verena

    2016-05-01

    Current climate trends resulting in rapid declines in sea ice and increasing water temperatures are likely to expand the northern geographic range and duration of favorable conditions for harmful algal blooms (HABs), making algal toxins a growing concern in Alaskan marine food webs. Two of the most common HAB toxins along the west coast of North America are the neurotoxins domoic acid (DA) and saxitoxin (STX). Over the last 20 years, DA toxicosis has caused significant illness and mortality in marine mammals along the west coast of the USA, but has not been reported to impact marine mammals foraging in Alaskan waters. Saxitoxin, the most potent of the paralytic shellfish poisoning toxins, has been well-documented in shellfish in the Aleutians and Gulf of Alaska for decades and associated with human illnesses and deaths due to consumption of toxic clams. There is little information regarding exposure of Alaskan marine mammals. Here, the spatial patterns and prevalence of DA and STX exposure in Alaskan marine mammals are documented in order to assess health risks to northern populations including those species that are important to the nutritional, cultural, and economic well-being of Alaskan coastal communities. In this study, 905 marine mammals from 13 species were sampled including; humpback whales, bowhead whales, beluga whales, harbor porpoises, northern fur seals, Steller sea lions, harbor seals, ringed seals, bearded seals, spotted seals, ribbon seals, Pacific walruses, and northern sea otters. Domoic acid was detected in all 13 species examined and had the greatest prevalence in bowhead whales (68%) and harbor seals (67%). Saxitoxin was detected in 10 of the 13 species, with the highest prevalence in humpback whales (50%) and bowhead whales (32%). Pacific walruses contained the highest concentrations of both STX and DA, with DA concentrations similar to those detected in California sea lions exhibiting clinical signs of DA toxicosis (seizures) off the coast

  10. 49 CFR Appendix B to Part 194 - High Volume Areas

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Glaise, AR. Wisconsin River Wisconsin Rapids, WI. Yukon River Fairbanks, AK. Other Navigable Waters Arthur Kill Channel, NY Cook Inlet, AK Freeport, TX Los Angeles/Long Beach Harbor, CA Port Lavaca, TX San...

  11. 49 CFR Appendix B to Part 194 - High Volume Areas

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Glaise, AR. Wisconsin River Wisconsin Rapids, WI. Yukon River Fairbanks, AK. Other Navigable Waters Arthur Kill Channel, NY Cook Inlet, AK Freeport, TX Los Angeles/Long Beach Harbor, CA Port Lavaca, TX San...

  12. 49 CFR Appendix B to Part 194 - High Volume Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Glaise, AR. Wisconsin River Wisconsin Rapids, WI. Yukon River Fairbanks, AK. Other Navigable Waters Arthur Kill Channel, NY Cook Inlet, AK Freeport, TX Los Angeles/Long Beach Harbor, CA Port Lavaca, TX San...

  13. 49 CFR Appendix B to Part 194 - High Volume Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Glaise, AR. Wisconsin River Wisconsin Rapids, WI. Yukon River Fairbanks, AK. Other Navigable Waters Arthur Kill Channel, NY Cook Inlet, AK Freeport, TX Los Angeles/Long Beach Harbor, CA Port Lavaca, TX San...

  14. Alaskan North Slope petroleum systems

    USGS Publications Warehouse

    Magoon, L.B.; Lillis, P.G.; Bird, K.J.; Lampe, C.; Peters, K.E.

    2003-01-01

    Six North Slope petroleum systems are identified, described, and mapped using oil-to-oil and oil-to-source rock correlations, pods of active source rock, and overburden rock packages. To map these systems, we assumed that: a) petroleum source rocks contain 3.2 wt. % organic carbon (TOC); b) immature oil-prone source rocks have hydrogen indices (HI) >300 (mg HC/gm TOC); c) the top and bottom of the petroleum (oil plus gas) window occur at vitrinite reflectance values of 0.6 and 1.0% Ro, respectively; and d) most hydrocarbons are expelled within the petroleum window. The six petroleum systems we have identified and mapped are: a) a southern system involving the Kuna-Lisburne source rock unit that was active during the Late Jurassic and Early Cretaceous; b) two western systems involving source rock in the Kingak-Blankenship, and GRZ-lower Torok source rock units that were active during the Albian; and c) three eastern systems involving the Shublik-Otuk, Hue Shale and Canning source rock units that were active during the Cenozoic. The GRZ-lower Torok in the west is correlative with the Hue Shale to the east. Four overburden rock packages controlled the time of expulsion and gross geometry of migration paths: a) a southern package of Early Cretaceous and older rocks structurally-thickened by early Brooks Range thrusting; b) a western package of Early Cretaceous rocks that filled the western part of the foreland basin; c) an eastern package of Late Cretaceous and Paleogene rocks that filled the eastern part of the foreland basin; and d) an offshore deltaic package of Neogene rocks deposited by the Colville, Canning, and Mackenzie rivers. This petroleum system poster is part of a series of Northern Alaska posters on modeling. The poster in this session by Saltus and Bird present gridded maps for the greater Northern Alaskan onshore and offshore that are used in the 3D modeling poster by Lampe and others. Posters on source rock units are by Keller and Bird as well as

  15. The Change in the Depiction of Alaskan Natives in Children's Fiction over Time.

    ERIC Educational Resources Information Center

    Epps, Dorothy Anne

    This study used content analysis to investigate the change, over time, in the depiction of Alaskan natives in children's fiction. The analysis was based on four broad categories: (1) physical traits, including physical features and types of clothing; (2) social traits, including language fluency, family associations, amount of formal education,…

  16. Alaskan Fish Gelatin Films: Thermal, Tensile, and Barrier Properties and Effects of Cross-linking

    USDA-ARS?s Scientific Manuscript database

    Gelatin was extracted from the skins of Alaska pollock (Theragra chalcogramma) and Alaska pink salmon (Oncorhynchus gorbuscha). These skins were by-products generated from the Alaskan fishing industry. Films were then cast from the fish gelatin and their thermal, tensile, water vapor permeability, o...

  17. North Pacific Atmospheric Circulation Change and Effective Moisture Variability in the Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Anderson, L.; Abbott, M. B.; Finney, B. P.; Burns, S. J.

    2005-12-01

    Analyses of sediment cores from Marcella Lake, a small, hydrologically-closed lake in the semi-arid interior southwest Yukon Territory, provide evaporation information for the last 4500 years at century-scale resolution. Water chemistry and oxygen isotope data from lakes and precipitation in the region indicate that oxygen isotope ratios from Marcella Lake are currently affected by summer evaporation. Past lake water changes were reconstructed from oxygen isotope analyses of sedimentary endogenic calcite. An oxygen isotope record of mean-annual precipitation from Jellybean Lake, a nearby open evaporation-insensitive system, provides simultaneous oxygen isotope ratio variations related to atmospheric circulation and ambient temperature. The difference between the two isotope records represents oxygen-18-enrichment in Marcella Lake water caused by summer evaporation. The oxygen isotope results indicate a prolonged period of lower evaporation between 3000 and 1500 cal BP, a finding that is consistent with independent evidence for higher lake levels during this period (i.e. increased effective moisture). The data indicate that since 1500 cal BP evaporation has increased and that during the last 200 years it has been greater than during the previous ~4000 years. Two prominent increases in evaporation occurred at 1200 and 200 cal BP. These shifts correspond with increases in aridity observed in other records of effective moisture variability in the interior southwest Yukon and with prominent changes in North Pacific atmospheric circulation patterns over the Gulf of Alaska.

  18. Multi-Year Estimates of Regional Alaskan Net CO2 Exchange: Constraining a Remote-Sensing Based Model with Aircraft Observations

    NASA Astrophysics Data System (ADS)

    Lindaas, J.; Commane, R.; Luus, K. A.; Chang, R. Y. W.; Miller, C. E.; Dinardo, S. J.; Henderson, J.; Mountain, M. E.; Karion, A.; Sweeney, C.; Miller, J. B.; Lin, J. C.; Daube, B. C.; Pittman, J. V.; Wofsy, S. C.

    2014-12-01

    The Alaskan region has historically been a sink of atmospheric CO2, but permafrost currently stores large amounts of carbon that are vulnerable to release to the atmosphere as northern high-latitudes continue to warm faster than the global average. We use aircraft CO2 data with a remote-sensing based model driven by MODIS satellite products and validated by CO2 flux tower data to calculate average daily CO2 fluxes for the region of Alaska during the growing seasons of 2012 and 2013. Atmospheric trace gases were measured during CARVE (Carbon in Arctic Reservoirs Vulnerability Experiment) aboard the NASA Sherpa C-23 aircraft. For profiles along the flight track, we couple the Weather Research and Forecasting (WRF) model with the Stochastic Time-Inverted Lagrangian Transport (STILT) model, and convolve these footprints of surface influence with our remote-sensing based model, the Polar Vegetation Photosynthesis Respiration Model (PolarVPRM). We are able to calculate average regional fluxes for each month by minimizing the difference between the data and model column integrals. Our results provide a snapshot of the current state of regional Alaskan growing season net ecosystem exchange (NEE). We are able to begin characterizing the interannual variation in Alaskan NEE and to inform future refinements in process-based modeling that will produce better estimates of past, present, and future pan-Arctic NEE. Understanding if/when/how the Alaskan region transitions from a sink to a source of CO2 is crucial to predicting the trajectory of future climate change.

  19. Air-cushion tankers for Alaskan North Slope oil

    NASA Technical Reports Server (NTRS)

    Anderson, J. L.

    1973-01-01

    A concept is described for transporting oil from the Arctic to southern markets in 10,000-ton, chemically fueled air-cushion vehicles (ACV's) configured as tankers. Based on preliminary cost estimates the conceptual ACV tanker system as tailored to the transportation of Alaskan North Slope oil could deliver the oil for about the same price per barrel as the proposed trans-Alaska pipeline with only one-third of the capital investment. The report includes the description of the conceptual system and its operation; preliminary cost estimates; an appraisal of ACV tanker development; and a comparison of system costs, versatility, vulnerability, and ecological effect with those of the trans-Alaska pipeline.

  20. Synoptic variability of extreme snowfall in the St. Elias Mountains, Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Andin, Caroline; Zdanowicz, Christian; Copland, Luke

    2015-04-01

    Glaciers in the Wrangell and St. Elias Mountains (Alaska and Yukon) are presently experiencing some of the highest regional wastage rates worldwide. While the effect of regional temperatures on glacier melt rates in this region has been investigated, comparatively little is known about how synoptic climate variations, for example in the position and strength of the Aleutian Low, modulate snow accumulation on these glaciers. Such information is needed to accurately forecast future wastage rates, glacier-water resource availability, and contributions to sea-level rise. Starting in 2000, automated weather stations (AWS) were established in the central St-Elias Mountains (Yukon) at altitudes ranging from 1190 to 5400 m asl, to collect climatological data in support of glaciological research. These data are the longest continuous year-round observations of surface climate ever obtained from this vast glaciated region. Here we present an analysis of snowfall events in the icefields of the St-Elias Mountains based on a decade-long series of AWS observations of snow accumulation. Specifically, we investigated the synoptic patterns and air mass trajectories associated with the largest snowfall events (> 25 cm/12 hours) that occurred between 2002 and 2012. Nearly 80% of these events occurred during the cold season (October-March), and in 74 % of cases the precipitating air masses originated from the North Pacific south of 50°N. Zonal air mass advection over Alaska, or from the Bering Sea or the Arctic Ocean, was comparatively rare (20%). Somewhat counter-intuitively, dominant surface winds in the St. Elias Mountains during high snowfall events were predominantly easterly, probably due to boundary-layer frictional drag and topographic funneling effects. Composite maps of sea-level pressure and 700 mb winds reveal that intense snowfall events between 2002 and 2012 were associated with synoptic situations characterized by a split, eastwardly-shifted or longitudinally

  1. 77 FR 45921 - Alaskan Fuel Hauling as a Restricted Category Special Purpose Flight Operation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-02

    ... operations, each aircraft used to transport fuel will be required to receive FAA certification for the... regulations. The special purpose of Alaskan fuel hauling was considered for aircraft type-certificated under... required for this special purpose. The fuel hauling system must be shown to meet the applicable...

  2. 20 CFR 416.1228 - Exclusion of Alaskan natives' stock in regional or village corporations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Exclusion of Alaskan natives' stock in regional or village corporations. 416.1228 Section 416.1228 Employees' Benefits SOCIAL SECURITY ADMINISTRATION SUPPLEMENTAL SECURITY INCOME FOR THE AGED, BLIND, AND DISABLED Resources and Exclusions § 416.1228...

  3. From Natural to Design River Deltas

    NASA Astrophysics Data System (ADS)

    Giosan, Liviu

    2016-04-01

    Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

  4. Dynamics of Active Layer Depth across Alaskan Tundra Ecosystems

    NASA Astrophysics Data System (ADS)

    Ma, C.; Zhang, X.; Song, X.; Xu, X.

    2016-12-01

    The thickness of the active layer, near-surface layer of Earth material above permafrost undergoing seasonal freezing and thawing, is of considerable importance in high-latitude environments because most physical, chemical, and biological processes in the permafrost region take place within it. The dynamics of active layer thickness (ALT) result from a combination of various factors including heat transfer, soil water content, soil texture, root density, stem density, moss layer thickness, organic layer thickness, etc. However, the magnitude and controls of ALT in the permafrost region remain uncertain. The purpose of this study is to improve our understanding of the dynamics of ALT across Alaskan tundra ecosystems and their controls at multiple scales, ranging from plots to entire Alaska. This study compiled a comprehensive dataset of ALT at site and regional scales across the Alaskan tundra ecosystems, and further analyzed ALT dynamics and their hierarchical controls. We found that air temperature played a predominant role on the seasonality of ALT, regulated by other physical and chemical factors including soil texture, moisture, and root density. The structural equation modeling (SEM) analysis confirmed the predominant role of physical controls (dominated by heat and soil properties), followed by chemical and biological factors. Then a simple empirical model was developed to reconstruct the ALT across the Alaska. The comparisons against field observational data show that the method used in this study is robust; the reconstructed time-series ALT across Alaska provides a valuable dataset source for understanding ALT and validating large-scale ecosystem models.

  5. Decomposition and arthropod succession in Whitehorse, Yukon Territory, Canada.

    PubMed

    Bygarski, Katherine; LeBlanc, Helene N

    2013-03-01

    Forensic arthropod succession patterns are known to vary between regions. However, the northern habitats of the globe have been largely left unstudied. Three pig carcasses were studied outdoors in Whitehorse, Yukon Territory. Adult and immature insects were collected for identification and comparison. The dominant Diptera and Coleoptera species at all carcasses were Protophormia terraneovae (R-D) (Fam: Calliphoridae) and Thanatophilus lapponicus (Herbst) (Fam: Silphidae), respectively. Rate of decomposition, patterns of Diptera and Coleoptera succession, and species dominance were shown to differ from previous studies in temperate regions, particularly as P. terraenovae showed complete dominance among blowfly species. Rate of decomposition through the first four stages was generally slow, and the last stage of decomposition was not observed at any carcass due to time constraints. It is concluded that biogeoclimatic range has a significant effect on insect presence and rate of decomposition, making it an important factor to consider when calculating a postmortem interval. © 2012 American Academy of Forensic Sciences.

  6. Microphysical Properties of Alaskan Volcanic Ash

    NASA Astrophysics Data System (ADS)

    Puthukkudy, A.; Espinosa, R.; Rocha Lima, A.; Remer, L.; Colarco, P. R.; Whelley, P.; Krotkov, N. A.; Young, K.; Dubovik, O.; Wallace, K.; Martins, J. V.

    2017-12-01

    Volcanic ash has the potential to cause a variety of severe problems for human health and the environment. Therefore, effective monitoring of the dispersion and fallout from volcanic ash clouds and characterization of the aerosol particle properties are essential. One way to acquire information from volcanic clouds is through satellite remote sensing: such images have greater coverage than ground-based observations and can present a "big picture" perspective. A challenge of remote sensing is that assumptions of certain properties of the target are often a pre-requisite for making accurate and quantitative retrievals. For example, detailed information about size distribution, sphericity, and optical properties of the constituent matter is needed or must be assumed. The same kind of information is also needed for atmospheric transport models to properly simulate the dispersion and fallout of volcanic ash. Presented here is a laboratory method to determine the microphysical and optical properties of volcanic ash samples collected from two Alaskan volcanoes with markedly different compositions. Our method uses a Polarized Imaging Nephelometer (PI-Neph) and a system that re-suspends the particles in an air flow. The PI-Neph measures angular light scattering and polarization of the re-suspended particles from 3o to 175o in scattering angle, with an angular resolution of 1o . Primary measurements include phase function and polarized phase function at three wavelengths (445nm, 532nm, and 661nm). Size distribution, sphericity, and complex refractive index are retrieved indirectly from the PI-Neph measurements using the GRASP (Generalized Retrieval of Aerosol and Surface Properties) inversion algorithm. We report the results of this method applied to samples from the Mt. Okmok (2008) and Mt. Katmai (1912) volcanic eruptions. To our knowledge, this is the first time direct measurements of phase matrix elements of ash from Mt. Okmok and Mt. Katmai have been reported. Retrieved

  7. Utility of a Work Process Classification System for characterizing non-fatal injuries in the Alaskan commercial fishing industry.

    PubMed

    Syron, Laura N; Lucas, Devin L; Bovbjerg, Viktor E; Bethel, Jeffrey W; Kincl, Laurel D

    2016-01-01

    The US commercial fishing industry is hazardous, as measured by mortality data. However, research on non-fatal injuries is limited. Non-fatal injuries constitute the majority of occupational injuries and can result in workers' lowered productivity and wages, lost quality of life, and disability. In the United States, a Work Process Classification System (WPCS) has previously been applied in Alaskan freezer-trawl and freezer-longline fleets to identify causes of injuries and specific hazards, but not to other fishing fleets. This descriptive epidemiologic study aimed to explore the application and modification of the WPCS in multiple Alaskan fleets, characterize non-fatal occupational injuries in these fleets, and identify work processes that could be targeted for further investigation and future injury prevention efforts. Traumatic, non-fatal injuries on-board Alaskan commercial fishing vessels were identified through United States Coast Guard investigative reports. Characteristics of injuries, as well as worker characteristics, were analysed. Injuries were coded using the WPCS. We successfully utilized the WPCS to code non-fatal injury cases (n = 136). The most frequent main work processes associated with non-fatal injuries included: on-board trawlers, handling frozen fish and processing the catch; on-board vessels using pot/trap gear, handling the gear and shooting/setting the gear; on-board longliners, traffic on board and hauling the gear; and on-board processor vessels, processing the catch, other work with the catch, and handling frozen fish. The study confirmed that a WPCS can be applied to multiple Alaskan fleets to identify hazardous tasks. Hazards were unique for each vessel gear type. Future injury prevention efforts should target work processes associated with the most frequent and most severe injuries. Future studies should establish time estimates for work processes in order to determine risk estimates. Efforts to improve non-fatal injury reporting

  8. Geologic setting of the Fortymile River area - Polyphase deformational history within part of the eastern Yukon-Tanana uplands of Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1998

    USGS Publications Warehouse

    Day, Warren C.; Gamble, Bruce M.; Henning, Mitchell W.; Smith, Bruce D.

    2000-01-01

    The Fortymile River area lies within the Yukon-Tanana lithotectonic terrane of east-central Alaska. This terrane is a mosaic of several lithotectonic assemblages, each with a coherent lithologic, metamorphic, and deformational history. Previous workers have shown that the Fortymile River area is underlain by rocks of the Seventymile, Taylor Mountain, and Nisutlin assemblages. The Taylor Mountain tectonostratigraphic assemblage is the most widespread within study area and is made up of amphibolite-grade Paleozoic(?) metamorphosed supracrustal rocks that have been intruded by plutonic rocks. The protoliths for the supracrustal rocks include mafic volcanic(?) rocks, graywacke, sulfide-rich siliciclastic sediments, quartz-rich sandstone, pelite, and marble, all of which are cut by late sulfide-bearing quartz veins. The mafic metavolcanic(?) rocks are of both tholeiitic and calc-alkalic affinity and have distinctly different rare-earth-element abundances. The supracrustal rocks are interpreted to have been deposited on a continental margin and (or) distal to an island-arc complex in a back-arc basin.The Steele Creek Dome Tonalite is defined herein as a composite body of foliated biotite-hornblende tonalitic orthogneiss containing country-rock rafts of paragneiss. The complex lies within the Taylor Mountain assemblage and has been tectonized and presumably recrystallized during regional Early Jurassic ductile deformation. The tonalite is compositionally similar to other volcanic-arc granites. The entire sequence was intruded by a Early Jurassic(?) hornblende monzodioritediorite-quartz diorite suite.The area has been subjected to at least three phases of deformation. The first (D1) produced a strong regional S1 schistosity and local mineral lineations. The second (D2) deformation generated tight to isoclinal F2 folds, folding the S1 schistosity and L1 mineral lineations, and was accompanied by a weak axial-planar S2 cleavage and both L2 mineral and stretching lineations

  9. The Climatology and Impacts of Atmospheric Rivers near the Coast of Southern Alaska

    NASA Astrophysics Data System (ADS)

    Nardi, K.; Barnes, E. A.; Mundhenk, B. D.

    2015-12-01

    Atmospheric rivers, narrow plumes of anomalously high tropospheric water vapor transport, frequently appear over the Pacific Ocean. Popularized by colloquialisms such as the "Pineapple Express," atmospheric rivers often interact with synoptic-scale disturbances to produce significant precipitation events over land masses. Previous research has focused extensively on the impacts of this phenomenon with respect to high-precipitation storms, namely during boreal winter, on the western coast of the contiguous United States. These events generate great scientific, political, and economic concerns for nearby cities, farms, and tourist destinations. Recently, researchers have investigated similar high-precipitation events along the southern coast of Alaska. Specifically, previous work has discussed several major events occurring during the September-November timeframe. One particular event, in October 2006, produced an all-time record for water levels at several river observation sites. This study examines the climatology of atmospheric rivers in the vicinity of southern Alaska. Data (1979-2014) from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) is used to detect atmospheric rivers approaching, and making landfall on, the southern Alaskan coast from the Kenai Peninsula to the Gulf of Alaska region. A seasonal cycle in the strength and frequency of atmospheric rivers over Alaska is shown. Furthermore, the study assesses the synoptic conditions coincident with atmospheric rivers and examines several instances of particularly strong precipitation events. For example, wintertime atmospheric river events tend to occur when a blocking high exists over southeastern Alaska. These results have the potential to help forecasters and emergency managers predict high-precipitation events and lessen potential negative impacts.

  10. Long-Term Effects of Otitis Media a Ten-Year Cohort Study of Alaskan Eskimo Children

    ERIC Educational Resources Information Center

    Kaplan, Gary J.; And Others

    1973-01-01

    Histories of ear disease, otoscopic examinations, and audiologic, intelligence, and achievement tests were obtained from a cohort of 489 Alaskan Eskimo children, followed through the first 10 years of life, to determine whether otitis media (middle ear inflammation) deleteriously affected intellectual functioning and achievement in school.…

  11. Water-quality data of lakes and wetlands in the Yukon Flats, Alaska, 2007–2009

    USGS Publications Warehouse

    Halm, Douglas R.; Guldager, Nikki

    2013-01-01

    Over a three-year period (2007–2009), in-situ measurements were taken and water-quality samples were collected from 111 lakes and wetlands located in the Yukon Flats, Alaska, during a U.S. Fish and Wildlife Service wetlands inventory. The U.S. Geological Survey performed the chemical analyses on the retrieved water-quality samples. Results from the analyses of water samples for dissolved carbon gases and carbon isotopes, hydrogen and oxygen stable isotopes, dissolved organic carbon, and major cations and anions, along with supporting site data, are presented in this report.

  12. Repeat Photography of Alaskan Glaciers and Landscapes as Both Art and as a Means of Communicating Climat Change

    NASA Astrophysics Data System (ADS)

    Molnia, B. F.

    2013-12-01

    For nearly 15 years, I have used repeat photography of Alaskan glaciers and landscapes to communicate to fellow scientists, policymakers, the media, and society that Alaskan glaciers and landscapes have been experiencing significant change in response to post-Little Ice Age climate change. I began this pursuit after being contacted by a U.S. Department of the Interior senior official who requested unequivocal and unambiguous documentation that climate change was real and underway. After considering several options as to how best respond to this challenge, I decided that if a picture is worth a thousand words, then a pair of photographs, both with the same field of view, spanning a century or more, and showing dramatic differences, would speak volumes to documenting that dynamic climate change is occurring over a very broad region of Alaska. To me, understating the obvious with photographic pairs was the best mechanism to present irrefutable, unambiguous, nonjudgmental, as well as unequivocal visual documentation that climate change was both underway and real. To date, more than 150 pairs that meet these criteria have been produced. What has surprised me most is that the many of the photographs contained in the pairs present beautiful images of stark, remote landscapes that convey the majestic nature of this dynamic region with its unique topography and landscapes. Typically, over periods of just several decades, the photographed landscapes change from black and white to blue and green. White ice becomes blue water and dark rock becomes lush vegetation. Repeat photography is a technique in which a historical photograph and a modern photograph, both having the same field of view, are compared and contrasted to quantitatively and qualitatively determine their similarities and differences. I have used this technique from both ground-based photo stations and airborne platforms at Alaskan locations in Kenai Fjords National Park, Glacier Bay National Park and Preserve

  13. Assessing hazard risk, cost of adaptation and traditional land use activities in the context of permafrost thaw in communities in Yukon and the Northwest Territories, Canada

    NASA Astrophysics Data System (ADS)

    Benkert, B.; Perrin, A.; Calmels, F.

    2015-12-01

    Together with its partners, the Northern Climate ExChange (NCE, part of the Yukon Research Centre at Yukon College) has been mapping permafrost-related hazard risk in northern communities since 2010. By integrating geoscience and climate project data, we have developed a series of community-scale hazard risk maps. The maps depict hazard risk in stoplight colours for easy interpretation, and support community-based, future-focused adaptation planning. Communities, First Nations, consultants and local regulatory agencies have used the hazard risk maps to site small-scale infrastructure projects, guide land planning processes, and assess suitability of land development applications. However, we know that assessing risk is only one step in integrating the implications of permafrost degradation in societal responses to environmental change. To build on our permafrost hazard risk maps, we are integrating economic principles and traditional land use elements. To assess economic implications of adaptation to permafrost change, we are working with geotechnical engineers to identify adaptation options (e.g., modified building techniques, permafrost thaw mitigation approaches) that suit the risks captured by our existing hazard risk maps. We layer this with an economic analysis of the costs associated with identified adaptation options, providing end-users with a more comprehensive basis upon which to make decisions related to infrastructure. NCE researchers have also integrated traditional land use activities in assessments of permafrost thaw risk, in a project led by Jean Marie River First Nation in the Northwest Territories. Here, the implications of permafrost degradation on food security and land use priorities were assessed by layering key game and gathering areas on permafrost thaw vulnerability maps. Results indicated that close to one quarter of big and small game habitats, and close to twenty percent of key furbearer and gathering areas within the First Nation

  14. An SNP within the Angiotensin-Converting Enzyme Distinguishes between Sprint and Distance Performing Alaskan Sled Dogs in a Candidate Gene Analysis

    PubMed Central

    Huson, Heather J.; Byers, Alexandra M.; Runstadler, Jonathan

    2011-01-01

    The Alaskan sled dog offers a unique mechanism for studying the genetics of elite athletic performance. They are a group of mixed breed dogs, comprised of multiple common breeds, and a unique breed entity seen only as a part of the sled dog mix. Alaskan sled dogs are divided into 2 primary groups as determined by their racing skills. Distance dogs are capable of running over 1000 miles in 10 days, whereas sprint dogs run much shorter distances, approximately 30 miles, but in faster times, that is, 18–25 mph. Finding the genes that distinguish these 2 types of performers is likely to illuminate genetic contributors to human athletic performance. In this study, we tested for association between polymorphisms in 2 candidate genes; angiotensin-converting enzyme (ACE) and myostatin (MSTN) and enhanced speed and endurance performance in 174 Alaskan sled dogs. We observed 81 novel genetic variants within the ACE gene and 4 within the MSTN gene, including a polymorphism within the ACE gene that significantly (P value 2.38 × 10−5) distinguished the sprint versus distance populations. PMID:21846742

  15. Understanding the Complex Dimensions of the Digital Divide: Lessons Learned in the Alaskan Arctic

    ERIC Educational Resources Information Center

    Subramony, Deepak Prem

    2007-01-01

    An ethnographic case study of Inupiat Eskimo in the Alaskan Arctic has provided insights into the complex nature of the sociological issues surrounding equitable access to technology tools and skills, which are referred to as the digital divide. These people can overcome the digital divide if they get the basic ready access to hardware and…

  16. American Indian/Alaskan Native Grandparents Raising Grandchildren: Findings from the Census 2000 Supplementary Survey

    ERIC Educational Resources Information Center

    Fuller-Thomson, Esme; Minkler, Meredith

    2005-01-01

    This article documents the prevalence and national profile of American Indian/Alaskan Native (AI/AN) grandparents who are raising their grandchildren, based on data from the American Community Survey/Census 2000 Supplementary Survey. In 2000 there were estimated to be nearly 53,000 AI/AN grandparent caregivers age 45 and older in the United…

  17. Urban American Indian/Alaskan Natives Compared to Non-Indians in Out-of-Home Care

    ERIC Educational Resources Information Center

    Carter, Vernon B.

    2011-01-01

    Historically, American Indian/Alaskan Native (AI/AN) children have been disproportionately represented in the foster care system. In this study, nationally representative child welfare data from October 1999 was used to compare urban AI/AN children to non-Indian children placed into out-of-home care. Compared to non-Indian children, urban AI/AN…

  18. Long-term climate patterns in Alaskan surface temperature and precipitation and their biological consequences

    USGS Publications Warehouse

    Simpson, James J.; Hufford, Gary L.; Fleming, Michael D.; Berg, Jared S.; Ashton, J.B.

    2002-01-01

    Mean monthly climate maps of Alaskan surface temperature and precipitation produced by the parameter-elevation regression on independent slopes model (PRISM) were analyzed. Alaska is divided into interior and coastal zones with consistent but different climatic variability separated by a transition region; it has maximum interannual variability but low long-term mean variability. Pacific decadal oscillation (PDO)- and El Nino Southern Oscillation (ENSO)-type events influence Alaska surface temperatures weakly (1-2/spl deg/C) statewide. PDO has a stronger influence than ENSO on precipitation but its influence is largely localized to coastal central Alaska. The strongest influence of Arctic oscillation (AO) occurs in northern and interior Alaskan precipitation. Four major ecosystems are defined. A major eco-transition zone occurs between the interior boreal forest and the coastal rainforest. Variability in insolation, surface temperature, precipitation, continentality, and seasonal changes in storm track direction explain the mapped ecosystems. Lack of westward expansion of the interior boreal forest into the western shrub tundra is influenced by the coastal marine boundary layer (enhanced cloud cover, reduced insolation, cooler surface and soil temperatures).

  19. The Colville River Delta as a Natural Recorder of Historical Changes in Organic Carbon Sources: Linkages with Climate Change

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Bianchi, T. S.; Allison, M. A.; Miller, A. J.; Marcantonio, F.

    2011-12-01

    The Colville River in Alaska is the largest river in North America that drains only continuously permafrosted tundra, and as such provides a unique signal of historical changes in one of the world's most vulnerable areas to climate changes. Additionally, the Colville flows into Simpson's Lagoon, an area of the Alaskan Beaufort coast protected by a barrier island chain, lessening the impacts of Arctic storms and ice grounding on sediment mixing. Cores collected from the Colville river delta in August of 2010 were found to be composed of muddy, organic-rich, well-laminated sediments. The 2.5 to 3 meter length of each core spans about one to two thousand years of Holocene history, including the entire Anthropocene and much of the late Holocene. Two cores were sampled for this data set - one from close to the river mouth, and one from farther east in Simpson's Lagoon. Samples were taken every 2 cm for the entire length of both cores. Bulk analyses including percent organic carbon, percent nitrogen, and stable carbon isotopic analysis were performed, and compound specific analyses including lignin-phenol and algal pigment analyses were performed. These analyses show significant changes in carbon storage over the time period represented by the cores, and appear to indicate changes in terrestrial carbon delivery to the cores over time. Specifically, the delivery of more isotopically depleted carbon from -27% at depth to values oscillating to -33% at the surface likely indicates two things, summarized below, which are also supported by variations in chemical biomarkers. These results show, one, an increase in the delivery to the lagoon of woody shrub inputs coupled with, two, an increase in the delivery of fresh-water phytoplankton detritus over the past few hundred years. These recorded changes in deltaic sediments may, in part, be consistent with previous observations of enhanced woody shrub encroachment and an increase in the areal extent of permafrost lakes on the

  20. The Missing Link: the Role of Floodplain Tie Channels in Connecting Off River Water Bodies to Lowland Rivers

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Dietrich, W. E.; Day, G.

    2005-05-01

    Along lowland river systems across the globe the exchange of water, sediment, carbon, nutrients and biota between main stem rivers and off-river water bodies (ORWB) is facilitated by the presence of stable secondary channels referred to here as tie channels. Sixty five percent of the ORWB along the middle Fly River in Papua New Guinea connect to the river through such channels. A similar percentage of the 37 ORWB located between Baton Rouge and Memphis on the lower Mississippi River at one time were linked to the river by tie or batture (as they are locally known) channels. Levee construction and other alterations aimed at flood control or navigation on the Mississippi have left only a handful of lakes connected to the river, of these, most are heavily altered by dredging or other modifications. Tie channels were also once common along major tributaries to the Mississippi, such as the Red River. In the much less disturbed Alaskan environment, tie channels are still common, especially along Birch Creek and the Koyukuk and Black rivers. Our studies on the Mississippi River, in Alaska and in Papua New Guinea indicate that tie channels possess a common channel form that is stable and self-maintaining for hundreds to possibly a thousand years. Tie channels exhibit narrow width to depth ratios (~ 5.5) and consistently scale in cross-sectional dimensions to the size of the lake into which they flow. Variations in river and lake stage drive flow bi-directionally through tie channels. A local high or sill in the bed of tie channels controls the degree and duration of connection between the river and ORWB, with many lakes becoming isolated during periods of low stage. The life-span of a tie channel depends on the rate of sediment loading to the ORWB. Our research indicates that this rate directly corresponds to the sediment loading in the main stem river. Along the Fly River, for example, a 5 to 7 fold increase in the river sediment load has resulted increases of 6 to 17

  1. Sensitivity analysis of lake mass balance in discontinuous permafrost: the example of disappearing Twelvemile Lake, Yukon Flats, Alaska (USA)

    USGS Publications Warehouse

    Jepsen, S.M.; Voss, C.I.; Walvoord, Michelle Ann; Rose, J.R.; Minsley, B.J.; Smith, B.D.

    2013-01-01

    Many lakes in northern high latitudes have undergone substantial changes in surface area over the last four decades, possibly as a result of climate warming. In the discontinuous permafrost of Yukon Flats, interior Alaska (USA), these changes have been non-uniform across adjacent watersheds, suggesting local controls on lake water budgets. Mechanisms that could explain the decreasing mass of one lake in Yukon Flats since the early 1980s, Twelvemile Lake, are identified via a scoping analysis that considers plausible changes in snowmelt mass and infiltration, permafrost distribution, and climate warming. Because predicted changes in evaporation (2 cmyr-1) are inadequate to explain the observed 17.5 cmyr-1 reduction in mass balance, other mechanisms are required. The most important potential mechanisms are found to involve: (1) changes in shallow, lateral groundwater flow to the lake possibly facilitated by vertical freeze-thaw migration of the permafrost table in gravel; (2) increased loss of lake water as downward groundwater flow through an open talik to a permeable subpermafrost flowpath; and (3) reduced snow meltwater inputs due to decreased snowpack mass and increased infiltration of snowmelt into, and subsequent evaporation from, fine-grained sediment mantling the permafrost-free lake basin.

  2. A study of unstable slopes in permafrost areas : Alaskan case studies used as a training tool.

    DOT National Transportation Integrated Search

    2011-12-01

    This report is the companion to the PowerPoint presentation for the project A Study of Unstable Slopes in Permafrost: Alaskan Case Studies Used as a Training Tool. The objectives of this study are 1) to provide a comprehensive review of literat...

  3. Traces of Old Glaciations in East-central Alaska

    NASA Astrophysics Data System (ADS)

    Duk-Rodkin, A.; Barendregt, R. W.; Weber, F.

    2001-12-01

    The East-central Alaska record of glaciations is similar to that preserved in the west-central Yukon. Surficial geologic mapping of the Yukon-Tanana upland has indicated at least 5 glacial periods including at least one early Holocene. The two earliest glaciations are of pre-Mid Pleistocene age and followed regional erosion and renewed uplift ca.4 Ma. The earliest glaciation of west-central Yukon occurred between 2.6 and 2.9 Ma, forming a continuous carapace of ice covering all the mountain ranges except for a small part of the Dawson Range. This first glaciation was also the most extensive in the region, and resulted in the NW diversion of Yukon River into Alaska by the Cordilleran Ice Sheet. Stratigraphic evidence of 6 glaciations of pre-Mid Pleistocene age is preserved in the western Canadian sector of the Tintina Trench. The limits of these glaciations have been mapped in Yukon on the basis of glacial landforms and the distribution of erratics. Although morphological features of older glaciations (Plio-Pleistocene) are generally not well preserved, there is relatively good control on the distribution of glacial features for two of the older glaciations in Mt.Harper, Alaska. Stratigraphic evidence of at least 3 older glaciations is found in the Goodpastor River. An initial magnetostratigraphic study of three sites in east-central Alaska have yielded normal magnetic polarities only. The sites are:(1) a relatively weathered lowermost till outcropping along Goodpastor River on the Yukon-Tanana upland,(2) an extremely weathered high level moraine (609m) on the western side of the Gerstle River, near Granite Mt.in the Alaska Range and (3)ca.914m pediment containing glacial erratics and a luvisol at its surface, located on Tok River, Tanana Valley, Alaska Range. The normal polarity of the first site likely indicates a Brunhes age rather than a normal subchron within the Matuyama Reversed Chron based on the modest degree of weathering of the till and lack of any

  4. Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-arctic Alaskan river

    USGS Publications Warehouse

    Benson, Emily R.; Wipfli, Mark S.; Clapcott, Joanne E.; Hughes, Nicholas F.

    2013-01-01

    Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream.

  5. Aerobic Methane Oxidation in Alaskan Lakes Along a Latitudinal Transect

    NASA Astrophysics Data System (ADS)

    Martinez-Cruz, K. C.; Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Anthony, P.; Thalasso, F.

    2013-12-01

    Karla Martinez-Cruz* **, Armando Sepulveda-Jauregui*, Katey M. Walter Anthony*, Peter Anthony*, and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Methane (CH4) is the third most important greenhouse gas in the atmosphere, after carbon dioxide and water vapor. Boreal lakes play an important role in the current global warming by contributing as much as 6% of global atmospheric CH4 sources annually. On the other hand, aerobic methane oxidation (methanotrophy) in lake water is a fundamental process in global methane cycling that reduces the amount of CH4 emissions to the atmosphere. Several environmental factors affect aerobic methane oxidation in the water column both directly and indirectly, including concentration of CH4 and O2, temperature and carbon budgets of lakes. We analyzed the potential of aerobic methane oxidation (PMO) rates in incubations of water collected from 30 Alaskan lakes along a north-south transect during winter and summer 2011. Our findings showed an effect of CH4 and O2 concentrations, temperature and yedoma thawing permafrost on PMO activity in the lake water. The highest PMO rates were observed in summer by lakes situated on thawing yedoma permafrost, most of them located in the interior of Alaska. We also estimated that 60-80% of all CH4 produced in Alaskan lakes could be taken up by methanotrophs in the lake water column, showing the significant influence of aerobic methane oxidation of boreal lakes to the global CH4 budget.

  6. GM1-gangliosidosis in Alaskan huskies: clinical and pathologic findings.

    PubMed

    Müller, G; Alldinger, S; Moritz, A; Zurbriggen, A; Kirchhof, N; Sewell, A; Baumgärtner, W

    2001-05-01

    Three Alaskan Huskies, two females and one male, were diagnosed with GM1-gangliosidosis. Clinically, diseased animals exhibited proportional dwarfism and developed progressive neurologic impairment with signs of cerebellar dysfunction at the age of 5-7 months. Skeletal lesions characterized by retarded enchondral ossification of vertebral epiphyses were revealed by radiographs of the male dog at 5.5 months of age. Histologic examination of the central nervous system (CNS) revealed that most neurons were enlarged with a foamy to granular cytoplasm due to tightly packed vacuoles that displaced the Nissl substance. Vacuoles in paraffin-embedded sections stained positively with Luxol fast blue and Grocott's method, and in frozen sections vacuoles were periodic acid-Schiff positive. Foamy vacuolation also occurred within neurons of the autonomic ganglia. Extracerebral cells such as macrophages and peripheral lymphocytes also displayed foamy cytoplasm and vacuolation. In the CNS of diseased animals, a mild demyelination and axonal degeneration was accompanied by a significant astrogliosis (P < 0.05) in the gray matter as compared with age- and sex-matched control dogs. There was also a significant loss (P < 0.05) of oligodendrocytes in the gray and white matter of affected animals as compared with controls. Ultrastructurally, the neuronal storage material consisted of numerous circular to concentric whorls of lamellated membranes or stacks of membranes in parallel arrays. GM1-gangliosidosis in Alaskan Huskies resembles beta-galactosidase deficiency in other canine breeds, and these CNS disorders may be a consequence of neuronal storage and disturbed myelin processing.

  7. Flood characteristics of Alaskan streams

    USGS Publications Warehouse

    Lamke, R.D.

    1979-01-01

    Peak discharge data for Alaskan streams are summarized and analyzed. Multiple-regression equations relating peak discharge magnitude and frequency to climatic and physical characteristics of 260 gaged basins were determined in order to estimate average recurrence interval of floods at ungaged sites. These equations are for 1.25-, 2-, 5-, 10-, 25-, and 50-year average recurrence intervals. In this report, Alaska was divided into two regions, one having a maritime climate with fall and winter rains and floods, the other having spring and summer floods of a variety or combinations of causes. Average standard errors of the six multiple-regression equations for these two regions were 48 and 74 percent, respectively. Maximum recorded floods at more than 400 sites throughout Alaska are tabulated. Maps showing lines of equal intensity of the principal climatic variables found to be significant (mean annual precipitation and mean minimum January temperature), and location of the 260 sites used in the multiple-regression analyses are included. Little flood data have been collected in western and arctic Alaska, and the predictive equations are therefore less reliable for those areas. (Woodard-USGS)

  8. Utility of a Work Process Classification System for characterizing non-fatal injuries in the Alaskan commercial fishing industry.

    PubMed

    Syron, Laura N; Lucas, Devin L; Bovbjerg, Viktor E; Bethel, Jeffrey W; Kincl, Laurel D

    2016-01-01

    Background The US commercial fishing industry is hazardous, as measured by mortality data. However, research on non-fatal injuries is limited. Non-fatal injuries constitute the majority of occupational injuries and can result in workers' lowered productivity and wages, lost quality of life, and disability. In the United States, a Work Process Classification System (WPCS) has previously been applied in Alaskan freezer-trawl and freezer-longline fleets to identify causes of injuries and specific hazards, but not to other fishing fleets. Objectives This descriptive epidemiologic study aimed to explore the application and modification of the WPCS in multiple Alaskan fleets, characterize non-fatal occupational injuries in these fleets, and identify work processes that could be targeted for further investigation and future injury prevention efforts. Design Traumatic, non-fatal injuries on-board Alaskan commercial fishing vessels were identified through United States Coast Guard investigative reports. Characteristics of injuries, as well as worker characteristics, were analysed. Injuries were coded using the WPCS. Results We successfully utilized the WPCS to code non-fatal injury cases (n = 136). The most frequent main work processes associated with non-fatal injuries included: on-board trawlers, handling frozen fish and processing the catch; on-board vessels using pot/trap gear, handling the gear and shooting/setting the gear; on-board longliners, traffic on board and hauling the gear; and on-board processor vessels, processing the catch, other work with the catch, and handling frozen fish. Conclusions The study confirmed that a WPCS can be applied to multiple Alaskan fleets to identify hazardous tasks. Hazards were unique for each vessel gear type. Future injury prevention efforts should target work processes associated with the most frequent and most severe injuries. Future studies should establish time estimates for work processes in order to determine risk estimates

  9. Utility of a Work Process Classification System for characterizing non-fatal injuries in the Alaskan commercial fishing industry

    PubMed Central

    Syron, Laura N.; Lucas, Devin L.; Bovbjerg, Viktor E.; Bethel, Jeffrey W.; Kincl, Laurel D.

    2016-01-01

    Background The US commercial fishing industry is hazardous, as measured by mortality data. However, research on non-fatal injuries is limited. Non-fatal injuries constitute the majority of occupational injuries and can result in workers’ lowered productivity and wages, lost quality of life, and disability. In the United States, a Work Process Classification System (WPCS) has previously been applied in Alaskan freezer-trawl and freezer-longline fleets to identify causes of injuries and specific hazards, but not to other fishing fleets. Objectives This descriptive epidemiologic study aimed to explore the application and modification of the WPCS in multiple Alaskan fleets, characterize non-fatal occupational injuries in these fleets, and identify work processes that could be targeted for further investigation and future injury prevention efforts. Design Traumatic, non-fatal injuries on-board Alaskan commercial fishing vessels were identified through United States Coast Guard investigative reports. Characteristics of injuries, as well as worker characteristics, were analysed. Injuries were coded using the WPCS. Results We successfully utilized the WPCS to code non-fatal injury cases (n = 136). The most frequent main work processes associated with non-fatal injuries included: on-board trawlers, handling frozen fish and processing the catch; on-board vessels using pot/trap gear, handling the gear and shooting/setting the gear; on-board longliners, traffic on board and hauling the gear; and on-board processor vessels, processing the catch, other work with the catch, and handling frozen fish. Conclusions The study confirmed that a WPCS can be applied to multiple Alaskan fleets to identify hazardous tasks. Hazards were unique for each vessel gear type. Future injury prevention efforts should target work processes associated with the most frequent and most severe injuries. Future studies should establish time estimates for work processes in order to determine risk

  10. Recurring middle Pleistocene outburst floods in east-central Alaska

    USGS Publications Warehouse

    Froese, D.G.; Smith, D.G.; Westgate, J.A.; Ager, T.A.; Preece, S.J.; Sandhu, A.; Enkin, R.J.; Weber, F.

    2003-01-01

    Recurring glacial outburst floods from the Yukon-Tanana Upland are inferred from sediments exposed along the Yukon River near the mouth of Charley River in east-central Alaska. Deposits range from imbricate gravel and granules indicating flow locally extending up the Yukon valley, to more distal sediments consisting of at least 10 couplets of planar sands, granules, and climbing ripples with up-valley paleocurrent indicators overlain by massive silt. An interglacial organic silt, occurring within the sequence, indicates at least two flood events are associated with an earlier glaciation, and at least three flood events are associated with a later glaciation which postdates the organic silt. A minimum age for the floods is provided by a glass fission track age of 560,000 ?? 80,000 yr on the GI tephra, which occurs 8 m above the flood beds. A maximum age of 780,000 yr for the floods is based on normal magnetic polarity of the sediments. These age constraints allow us to correlate the flood events to the early-middle Pleistocene. And further, the outburst floods indicate extensive glaciation of the Yukon-Tanana Upland during the early-middle Pleistocene, likely representing the most extensive Pleistocene glaciation of the area. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  11. Placer and lode platinum-group minerals in south Kalimantan, Indonesia: evidence for derivation from Alaskan-type ultramafic intrusions

    USGS Publications Warehouse

    Zientek, M.L.

    1992-01-01

    Platinum-group minerals occur in significant proportions in placer deposits in several localities in South Kalimantan. They consist of Pt-Fe alloy that may be intergrown with or contain inclusions of Ir-Os-Ru alloy, laurite and chromite. Alluvial PGM found along Sungai Tambanio are in part derived from chromatite schlieren in dunitic bodies intruded into clinopyroxene cumulates that may be part of an Alaskan-type ultramafic complex. A chromitite schlieren in serpentinite from one of these dunitic bodies is anomalous in PGE. The chondrite-normalized PGE pattern for this rock, pan concentrates from this area, and PGM concentrates from diamond-Au-PGM placer deposits have an "M'-shaped pattern enriched in Ir and Pt that is typical of PGE-mineralization associated with Alaskan-type ultramafic complexes. -Authors

  12. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    NASA Astrophysics Data System (ADS)

    Stubbins, Aron; Spencer, Robert; Mann, Paul; Holmes, R.; McClelland, James; Niggemann, Jutta; Dittmar, Thorsten

    2015-10-01

    Wildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  13. 43 CFR 3101.2-1 - Public domain lands.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... to the left limit of the Tanana River (63°9′38″ north latitude, 142°20′52″ west longitude), then westerly along the left limit to the confluence of the Tanana and Yukon Rivers, and then along the left...

  14. 43 CFR 3101.2-1 - Public domain lands.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... to the left limit of the Tanana River (63°9′38″ north latitude, 142°20′52″ west longitude), then westerly along the left limit to the confluence of the Tanana and Yukon Rivers, and then along the left...

  15. 43 CFR 3101.2-1 - Public domain lands.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... to the left limit of the Tanana River (63°9′38″ north latitude, 142°20′52″ west longitude), then westerly along the left limit to the confluence of the Tanana and Yukon Rivers, and then along the left...

  16. 43 CFR 3101.2-1 - Public domain lands.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... to the left limit of the Tanana River (63°9′38″ north latitude, 142°20′52″ west longitude), then westerly along the left limit to the confluence of the Tanana and Yukon Rivers, and then along the left...

  17. The role of DOM in nitrogen processing in streams across arctic regions affected by fire

    NASA Astrophysics Data System (ADS)

    Rodriguez-Cardona, B.; Schade, J. D.; Holmes, R. M.; Natali, S.; Mann, P. J.; Wymore, A.; Coble, A. A.; Prokishkin, A. S.; Zito, P.; Podgorski, D. C.; Spencer, R. G.; McDowell, W. H.

    2017-12-01

    In stream ecosystems, inputs of dissolved organic carbon (DOC) have a strong influence on nitrogen (N) processing. Previous studies have demonstrated that increases in DOC concentrations can promote greater N removal in many stream ecosystems. Most of what we know about C and N coupling comes from studies of temperate streams; less is known about this relationship in the Arctic. Streams in Arctic ecosystems are facing rapid changes in climate and disturbance regimes, in particular increasing fire frequencies that are likely to alter biogeochemical cycles. Although fires can lead to increases in NO3 concentrations in streams, the effects of fire on DOC (concentration and composition) have been difficult to generalize. We studied the relationships between DOC and N in two locations; the Central Siberian Plateau, Russia and the Yukon-Kuskokwim (YK) River Delta, Alaska. Streams in both regions show increases in NO3 concentrations after fire, while DOC concentrations decrease in Siberia but increase in streams within the YK-Delta. These patterns in DOC and NO3 create a gradient in DOC and nutrient concentrations, allowing us to study this coupling in a wider Pan-Arctic scope. In order to assess the role of DOC in Arctic N processing, we conducted NO3 and NH4 additions to stream microcosms at the Alaskan site as well as whole-stream additions in Siberia. We hypothesized that nutrient uptake would be high in older burn sites of Siberia and recently burned sites in the YK-Delta, due to greater DOC concentrations and availability. Our results suggest that nitrogen dynamics in the Alaskan sites is strongly responsive to C availability, but is less so in Siberian sites. The potential impacts of permafrost thawing and fires on DOM and nutrient dynamics thus appear to not be consistent across the Arctic suggesting that different regions of the Arctic have unique biogeochemical controls.

  18. Deg Xinag. Ingalik Noun Dictionary (Preliminary).

    ERIC Educational Resources Information Center

    Kari, James, Comp.

    This dictionary contains lists of nouns in the Deg Xinag or Ingalik language as spoken in the Yukon River villages of Anvik, Shageluk, and Holy Cross, and the Kuskokwim River village of Stony River. After a presentation of the Ingalik alphabet, the nouns, with English equivalents, are listed according to the following categories: mammals; fish;…

  19. Thematic mapper study of Alaskan ophiolites

    NASA Technical Reports Server (NTRS)

    Bird, John M.

    1988-01-01

    The two principle objectives of the project Thematic Mapper Study of Alaskan Ophiolites were to further develop techniques for producing geologic maps, and to study the tectonics of the ophiolite terrains of the Brooks Range and Ruby Geanticline of northern Alaska. Ophiolites, sections of oceanic lithosphere emplaced along island arcs and continental margins, are important to the understanding of mountain belt evolution. Ophiolites also provide an opportunity to study the structural, lithologic, and geochemical characteristics of ocean lithosphere, yielding a better understanding of the processes forming lithosphere. The first part of the report is a description of the methods and results of the TM mapping and gravity modeling. The second part includes papers being prepared for publication. These papers are the following: (1) an analysis of basalt spectral variations; (2) a study of basalt geochemical variations; (3) an examination of the cooling history of the ophiolites using radiometric data; (4) an analysis of shortening produced by thrusting during the Brooks Range orogeny; and (5) a study of an ophiolite using digital aeromagnetic and topographic data. Additional papers are in preparation.

  20. Overview of environmental and hydrogeologic conditions at Saint Marys, Alaska

    USGS Publications Warehouse

    Nakanishi, Allan S.; Dorava, Joseph M.

    1994-01-01

    The Federal Aviation Administration (FAA) owns or operates airway support facilities near Saint Marys along the Yukon River in west-central Alaska. The FAA is evaluating the severity of environmental contamination and options for remediation of environmental contamination at their facilities. Saint Marys is on a flood plain near the continence of the Yukon and Andreafsky Rivers and has long cold winters and short summers. Residents obtain their drinking water from an infiltration gallery fed by a creek near the village. Surface spills and disposal of hazardous materials combined with potential flooding may affect the quality of the surface and ground water. Alternative drinking-water sources are available, but would likely cost more than existing supplies to develop.

  1. Establishing an Alaskan birch syrup industry: Birch Syrup—It’s the Un-maple!TM

    Treesearch

    Marlene Cameron

    2001-01-01

    Ten years ago a small group of Alaskans began commercial production of birch syrup from the sap of the paper birch, Betula papyrifera, and established an industry that is expanding in response to demand and has the potential to make a significant contribution to Alaska's economy. There are still many problems to be solved; research and...

  2. Comparison of Alaskan Flood Stages: Annual Exceedance Probability vs. Impact Based Stages and Recommendations for the Future

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.

    2016-12-01

    The Alaska River Forecasting Center (APRFC) issues water level forecasts that are used in conjunction with established flood stages to provide flood warning and advisory information to the public. The APRFC typically establishes flood stages based on observed impacts but Alaska has sparse empirical data (e.g., few impact surveys). Thus service hydrologists in Alaska use flood frequency analysis (LP3 distribution) to estimate flood stages from annual exceedance probabilities (AEPs) (Curran et al, 2016). Previously, the APRFC has maintained that bankfull stage corresponds to the 50% AEP, minor to 10-20% AEP, moderate to 2.5-7% AEP, and major to 1-2% AEP, but we now need to statistically verify this relationship. Our objective is therefore to validate the relationship between flood stages and stage associated with the 50, 20, 10, 4, 2, 1, 0.2, and 0.5 AEPs to provide recommendations for improved flood forecasting. We studied the relationship between AEP and flood stage for all gages (56) used by the APRFC that had rating curves not older than 3 years, flood stages based on observed impacts, and at least 10 years of peak annual stage data. The analysis found relatively strong relationships for all flood stages, except for bankfull stage, but with some differences when compared to the traditionally referenced relationship. Major flood stage appears to be most similar to the 1-.2% AEP (100-500 year RI) while moderate flood stage best fits the 2-4% AEP (25-50 year interval). Gages showing a difference in stage of 2 ft or greater exhibited this difference across all flood stages, which we link to site specific qualities such as susceptibility to ice-jam flooding. We present this method as a possible application to Alaskan Rivers as a general flood stage guideline.

  3. Bioaccumulation of petroleum hydrocarbons in arctic amphipods in the oil development area of the Alaskan Beaufort Sea.

    PubMed

    Neff, Jerry M; Durell, Gregory S

    2012-04-01

    An objective of a multiyear monitoring program, sponsored by the US Department of the Interior, Bureau of Ocean Energy Management was to examine temporal and spatial changes in chemical and biological characteristics of the Arctic marine environment resulting from offshore oil exploration and development activities in the development area of the Alaskan Beaufort Sea. To determine if petroleum hydrocarbons from offshore oil operations are entering the Beaufort Sea food web, we measured concentrations of hydrocarbons in tissues of amphipods, Anonyx nugax, sediments, Northstar crude oil, and coastal peat, collected between 1999 and 2006 throughout the development area. Mean concentrations of polycyclic aromatic hydrocarbons (PAH), saturated hydrocarbons (SHC), and sterane and triterpane petroleum biomarkers (StTr) were not significantly different in amphipods near the Northstar oil production facility, before and after it came on line in 2001, and in amphipods from elsewhere in the study area. Forensic analysis of the profiles (relative composition and concentrations) of the 3 hydrocarbon classes revealed that hydrocarbon compositions were different in amphipods, surface sediments where the amphipods were collected, Northstar crude oil, and peat from the deltas of 4 North Slope rivers. Amphipods and sediments contained a mixture of petrogenic, pyrogenic, and biogenic PAH. The SHC in amphipods were dominated by pristane derived from zooplankton, indicating that the SHC were primarily from the amphipod diet of zooplankton detritus. The petroleum biomarker StTr profiles did not resemble those in Northstar crude oil. The forensic analysis revealed that hydrocarbons in amphipod tissues were not from oil production at Northstar. Hydrocarbons in amphipod tissues were primarily from their diet and from river runoff and coastal erosion of natural diagenic and fossil terrestrial materials, including seep oils, kerogens, and peat. Offshore oil and gas exploration and development

  4. Quantifying the historic and future distribution of fire in Alaskan tundra ecosystems

    NASA Astrophysics Data System (ADS)

    Young, A. M.; Higuera, P. E.; Duffy, P. A.

    2012-12-01

    During the past 60 years fire has been relatively rare and small in size within tundra ecosystems. However, historical observations and paleoecological evidence indicates that fire regimes vary widely across Alaskan tundra, in both space and time. These lines of evidence suggest that fire occupies a highly specified niche or ecological space in Alaskan tundra, which may change significantly with future climate warming. The objective of this research was to quantify the relationships between fire occurrence and different seasonal climate variables, and to begin to make inferences about future distributions of fire across the tundra landscape. The results of this research will ultimately contribute to the goal of summarizing the linkages that exist among climate, vegetation, and fire in the historical record, and for making predictions concerning fire disturbance in tundra ecosystems throughout the next century. Historic tundra fires occurred non-randomly across space, and a relationship exists between fire occurrence and warm, dry climates. We quantified this relationship with generalized boosting models (GBM) using datasets of downscaled temperature and precipitation (2 km, 1971-2000), and historic records of tundra area burned (1950-2010). The GBM used six seasonal climate variables, focused on growing season temperature and precipitation, to predict the probability of fire occurrence over the 1950-2010 time period. To understand implications of these historic relationships given ongoing climate warming, we constructed future climatologies of temperature and precipitation for the five GCMs which performed best in Alaska under the IPCC AR4 A1B (middle-of-the-road) emissions scenario for the time period 2021-2050. The GBM performed well predicting the observed spatial distribution of tundra area burned, capturing key regions which experienced the most fire activity from 1950-2010. The mean temperature of the warmest month (MeanMaxTemp) was the most influential

  5. Geomorphology of the lower Copper River, Alaska

    USGS Publications Warehouse

    Brabets, T.P.

    1996-01-01

    The Copper River, located in southcentral Alaska, drains an area of more than 24,000 square miles. About 30 miles above its mouth, this large river enters Miles Lake, a proglacial lake formed by the retreat of Miles Glacier. Downstream from the outlet of Miles Lake, the Copper River flows past the face of Childs Glacier before it enters a large, broad, alluvial flood plain. The Copper River Highway traverses this flood plain and in 1996, 11 bridges were located along this section of the highway. These bridges cross parts or all of the Copper River and in recent years, some of these bridges have sustained serious damage due to the changing course of the Copper River. Although the annual mean discharge of the lower Copper River is 57,400 cubic feet per second, most of the flow occurs during the summer months from snowmelt, rainfall, and glacial melt. Approximately every six years, an outburst flood from Van Cleve Lake, a glacier-dammed lake formed by Miles Glacier, releases approximately 1 million acre-feet of water into the Copper River. At the peak outflow rate from Van Cleve Lake, the flow of the Copper River will increase an additional 140,000 and 190,000 cubic feet per second. Bedload sampling and continuous seismic reflection were used to show that Miles Lake traps virtually all the bedload being transported by the Copper River as it enters the lake from the north. The reservoir-like effect of Miles Lake results in the armoring of the channel of the Copper River downstream from Miles Lakes, past Childs Glacier, until it reaches the alluvial flood plain. At this point, bedload transport begins again. The lower Copper River transports 69 million tons per year of suspended sediment, approximately the same quantity as the Yukon River, which drains an area of more than 300,000 square miles. By correlating concurrent flows from a long-term streamflow- gaging station on the Copper River with a short-term streamflow-gaging station at the outlet of Miles Lake, long

  6. Geomorphology of the lower Copper River, Alaska

    USGS Publications Warehouse

    Brabets, Timothy P.

    1997-01-01

    The Copper River, located in southcentral Alaska, drains an area of more than 24,000 square miles. About 30 miles above its mouth, this large river enters Miles Lake, a proglacial lake formed by the retreat of Miles Glacier. Downstream from the outlet of Miles Lake, the Copper River flows past the face of Childs Glacier before it enters a large, broad, alluvial flood plain. The Copper River Highway traverses this flood plain and in 1995, 11 bridges were located along this section of the highway. These bridges cross parts of the Copper River and in recent years, some of these bridges have sustained serious damage due to the changing course of the Copper River. Although the annual mean discharge of the lower Copper River is 57,400 cubic feet per second, most of the flow occurs during the summer months from snowmelt, rainfall, and glacial melt. Approximately every six years, an outburst flood from Van Cleve Lake, a glacier-dammed lake formed by Miles Glacier, releases approximately 1 million acre-feet of water into the Copper River. When the outflow rate from Van Cleve Lake reaches it peak, the flow of the Copper River will increase between 150,000 to 190,000 cubic feet per second. Data collected by bedload sampling and continuous seismic reflection indicated that Miles Lake traps virtually all the bedload being transported by the Copper River as it enters the lake from the north. The reservoir-like effect of Miles Lake results in the armoring of the channel of the Copper River downstream from Miles Lake, past Childs Glacier, until it reaches the alluvial flood plain. At this point, bedload transport begins again. The lower Copper River transports 69 million tons per year of suspended sediment, approximately the same quantity as the Yukon River, which drains an area of more than 300,000 square miles. By correlating concurrent flows from a long-term streamflow-gaging station on the Copper River with a short-term streamflow-gaging station at the outlet of Miles Lake

  7. Intensive Evaluation of Satellite TV Impact on Four Alaskan Villages. Supplement to Basic ESCD Evaluation Design.

    ERIC Educational Resources Information Center

    Practical Concepts, Inc., Washington, DC.

    A supplement to the final report, "Design for an Analysis and Assessment of the Education Satellite Communications Demonstration (ESCD)," this document is both: (1) a separable, sociologically oriented evaluation of the ESCD impact on Alaskan native villages; and (2) a direct extension of the work described in sections 4 and 5 in the…

  8. Sarcocystis arctica (Apicomplexa: Sarcocystidae): ultrastructural description and its new host record, the Alaskan wolf (Canis lupus

    USDA-ARS?s Scientific Manuscript database

    Sarcocystis sarcocysts are common in muscles of herbivores but are rare in muscles of carnivores. Here, we report sarcocysts in muscle of an Alaskan wolf (Canis lupus) from Alaska, USA for the first time. Sarcocysts extracted from tongue of the wolf were up to 900 µm long, slender, and appeared to h...

  9. Applications of remote sensing data to the Alaskan environment

    NASA Technical Reports Server (NTRS)

    Belon, A. E.; Iller, J. M.

    1973-01-01

    The ERTS program provides a means to overcome the formidable logistic and economic costs of preparing environmental surveys of the vast and relatively unexplored regions of Alaska. There is an excellent potential in satellite remote sensing to benefit Federal, state, local, and private agencies, by providing a new synoptic data base which is necessary for the preparation of the needed surveys and the search for solutions to environmental management problems. One approach in coupling satellite data to Alaskan problems is a major program initiated by the University of Alaska and funded by NASA's Goddard Space Flight Center. This included 12 projects whose aims were to study the feasibility of applying ERTS data to the disciplines of ecology, agriculture, hydrology, wildlife management, oceanography, geology, glaciology, volcanology, and archaeology.

  10. Evaluation of the composite burn index for assessing fire severity in Alaskan black spruce forests

    Treesearch

    Eric S. Kasischke; Merritt R. Turetsky; Roger D. Ottmar; Nancy H.F. French; Elizabeth E. Hoy; Evan S. Kane

    2008-01-01

    We evaluated the utility of the composite burn index (CBI) for estimating fire severity in Alaskan black spruce forests by comparing data from 81 plots located in 2004 and 2005 fire events. We collected data to estimate the CBI and quantify crown damage, percentage of trees standing after the fire, depth of the organic layer remaining after the fire, depth of burning...

  11. TISSUE DISTRIBUTION OF PCBS AND ORGANOCHLORINE PESTICIDES IN ALASKAN NORTHERN FUR SEALS: COMPARISON OF VARIOUS CONGENER CLASSIFICATION SCHEMES

    USDA-ARS?s Scientific Manuscript database

    Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are believed to adversely affect reproduction and cause health problems in Pinnipeds 1-4. In this study, 145 PCB congeners and OCPs were analyzed in 10 juvenile male northern fur seals, Callorhinus ursinus, collected from Alaskan...

  12. Social and Cognitive Effects of the Introduction of Television on Rural Alaskan Native Children. Final Report.

    ERIC Educational Resources Information Center

    Forbes, Norma; And Others

    A 5-year study of the social and cognitive effects of the introduction of commercial and educational television on rural Alaskan children utilized a variety of social and cognitive measures given to both longitudinal and cross-sectional samples of grade-school children: in 1977, when no participating village received television; in 1979, when half…

  13. Yukon-Kuskokwim Delta Berry Outlook: Co-Producing Knowledge to Better Understand Changing Resources.

    NASA Astrophysics Data System (ADS)

    Herman-Mercer, N. M.; Loehman, R.; Paniyak, C.; Toohey, R.; Tonuchuk, V., Jr.

    2017-12-01

    The Yukon-Kuskokwim (YK) Delta Berry Outlook is a collaborative, interdisciplinary project with the objective of understanding changing berry resources in the YK Delta. Berries are an important subsistence resource culturally and nutritionally for Alaska Natives as well as an important resource for the large migratory bird population in the Yukon Delta wildlife refuge. As such understanding berry resources is essential for human and bird populations and is of interest to communities and land managers alike. Partnering with Tribal Councils in four YK Delta communities, cultural consensus surveys were administered to explore local knowledge concerning ecological drivers of berry abundance and distribution. Cultural consensus surveys are a specific type of survey, in which respondents are asked a series of questions concerning a particular knowledge, here ecological drivers of berry resources. Surveys were administered in four Alaska Native villages concerning five prominent berry species. Respondents identified five ecological drivers, and results suggest that drivers are not uniform across berry species. For example, salmonberries were identified as ripening earlier in the season than in the past though the timing of other berry species has generally stayed the same. Additionally, respondents were asked to map harvesting locations for each of these berries and indicate if locations had changed over time. The resulting maps have allowed us to identify locations of high density harvesting for specific berries as well as the different distances traveled in different communities. Identifying important berry harvesting locations is critical for understanding location specific changes that may occur and have the potential to impact the abundance and distribution of berries. The survey and mapping results were used to inform ecological modelling and forecast potential berry responses to future climate scenarios. This presentation will focus on the results of combining data

  14. Apolipoprotein E isoforms 3/3 and 3/4 differentially interact with circulating stearic, palmitic, and oleic fatty acids and lipid levels in Alaskan Natives.

    PubMed

    Castellanos-Tapia, Lyssia; López-Alvarenga, Juan Carlos; Ebbesson, Sven O E; Ebbesson, Lars O E; Tejero, M Elizabeth

    2015-04-01

    Lifestyle changes in Alaskan Natives have been related to the increase of cardiovascular disease and metabolic syndrome in the last decades. Variation of the apolipoprotein E (Apo E) genotype may contribute to the diverse response to diet in lipid metabolism and influence the association between fatty acids in plasma and risk factors for cardiovascular disease. The aim of this investigation was to analyze the interaction between Apo E isoforms and plasma fatty acids, influencing phenotypes related to metabolic diseases in Alaskan Natives. A sample of 427 adult Siberian Yupik Alaskan Natives was included. Fasting glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, Apo A1, and Apo B plasma concentrations were measured using reference methods. Concentrations of 13 fatty acids in fasting plasma were analyzed by gas chromatography, and Apo E variants were identified. Analyses of covariance were conducted to identify Apo E isoform and fatty acid main effects and multiplicative interactions. The means for body mass index and age were 26 ± 5.2 and 47 ± 1.5, respectively. Significant main effects were observed for variation in Apo E and different fatty acids influencing Apo B levels, triglycerides, and total cholesterol. Significant interactions were found between Apo E isoform and selected fatty acids influencing total cholesterol, triglycerides, and Apo B concentrations. In summary, Apo E3/3 and 3/4 isoforms had significant interactions with circulating levels of stearic, palmitic, oleic fatty acids, and phenotypes of lipid metabolism in Alaskan Natives. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Lake carbonate-δ18 records from the Yukon Territory, Canada: Little Ice Age moisture variability and patterns

    USGS Publications Warehouse

    Anderson, Lesleigh; Finney, Bruce P.; Shapley, Mark D.

    2011-01-01

    A 1000-yr history of climate change in the central Yukon Territory, Canada, is inferred from sediment composition and isotope geochemistry from small, groundwater fed, Seven Mile Lake. Recent observations of lake-water δ18O, lake level, river discharge, and climate variations, suggest that changes in regional effective moisture (precipitation minus evaporation) are reflected by the lake’s hydrologic balance. The observations indicate that the lake is currently 18O-enriched by summer evaporation and that during years of increased precipitation, when groundwater inflow rates to the lake increase, lake-water δ18O values decrease. Past lake-water δ18O values are inferred from oxygen isotope ratios of fine-grained sedimentary endogenic carbonate. Variations in carbonate δ18O, supplemented by those in carbonate and organic δ13C, C/N ratios, and organic carbon, carbonate and biogenic silica accumulation rates, document changes in effective moisture at decadal time scales during the early Little Ice Age period to present. Results indicate that between ∼AD 1000 and 1600, effective moisture was higher than today. A shift to more arid climate conditions occurred after ∼AD 1650. The 19th and 20th centuries have been the driest of the past millennium. Temporal variations correspond with inferred shifts in summer evaporation from Marcella Lake δ18O, a similarly small, stratified, alkaline lake located ∼250 km to the southwest, suggesting that the combined reconstructions accurately document the regional paleoclimate of the east-central interior. Comparison with regional glacial activity suggests differing regional moisture patterns during early and late Little Ice Age advances.

  16. The role of windstorm exposure and yellow cedar decline on landslide susceptibility in southeast Alaskan temperate rainforests

    Treesearch

    Brian Buma; Adelaide C. Johnson

    2015-01-01

    Interactions between ecological disturbances have the potential to alter other disturbances and their associated regimes, such as the likelihood, severity, and extent of events. The influence of exposure to wind and yellow cedar decline on the landslide regime of Alaskan temperate rainforests was explored using presence-only modeling techniques. The wind regime was...

  17. Evaluating the potential of Landsat TM/ETM+ imagery for assessing fire severity in Alaskan black spruce forests

    Treesearch

    Elizabeth E. Hoy; Nancy H.F. French; Merritt R. Turetsky; Simon N. Trigg; Eric S. Kasischke

    2008-01-01

    Satellite remotely sensed data of fire disturbance offers important information; however, current methods to study fire severity may need modifications for boreal regions. We assessed the potential of the differenced Normalized Burn Ratio (dNBR) and other spectroscopic indices and image transforms derived from Landsat TM/ETM+ data for mapping fire severity in Alaskan...

  18. Mineralogical and Geochemical Study of Titanite Associated With Copper Mineralization in the Hopper Property, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Blumenthal, V. H.; Linnen, R. L.

    2009-05-01

    Copper mineralization in central Yukon is well known, but the metallogeny of the Ruby Range batholith, west of the copper belt, is poorly understood. The Hopper property, situated in the south western part of the Yukon in the Yukon-Tanana terrane, contains copper mineralization hosted by granodiorite and quartz feldspar porphyry of cal-alkaline affinity. These rock units, interpreted to be part of the Ruby Range batholith, intruded metasediments of the Ashihik Metamorphic Suite rocks. Mafic dykes cross cut the intrusion followed by aplite dykes. Small occurrences of skarn also occur in the area and some of these contain copper mineralization. The copper mineralization at the Hopper property appears to have a porphyry-type affinity. However, it is associated with a shear zone and propylitic alteration unlike other typical copper porphyry-type deposits. This raises the question whether or not the mineralization is orthomagmatic in origin, i.e., whether or not this is a true porphyry system. The main zone of mineralization is 1 kilometer long and 0.5 kilometer wide. It is characterized by disseminated chalcopyrite and pyrite, which also occur along fractures. Molybdenite mineralization was found to be associated with slickensides. Alteration minerals associated with the copper mineralization are chlorite, epidote-clinozoisite, carbonate and titanite. Chlorite and epidote-clinozoisite are concentrated in the mineralized zone, whereas an earlier potassic alteration shows a weaker spatial correlation with the mineralization. The association of the mineralization with propylitic alteration leads us to believe the mineralization is shear related, although a deeper porphyritic system may be present at depth. Two populations of titanite at the Hopper property are recognized based on their shape, size and association with other minerals. The first population, defined by a length of 100 micrometers to 1 centimeter, euhedral boundaries, and planar contacts with other magmatic

  19. The Rivers Run Down to the Sea: Safety for Small Boats.

    ERIC Educational Resources Information Center

    Keller, Rosanne

    Part of a series of home literacy readers with conversational text and sketches, this booklet addresses water safety in the Alaskan summer environment. Alaskan villages are generally located near slough, creek, lake or ocean. At the end of winter, the ice floes go out, and where there was snow there is water. Summer activities include use of…

  20. Molecular investigations into a globally important carbon pool: Permafrost-protected carbon in Alaskan soils

    USGS Publications Warehouse

    Waldrop, M.P.; Wickland, K.P.; White, Rickie; Berhe, A.A.; Harden, J.W.; Romanovsky, V.E.

    2010-01-01

    The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in permafrost soils limit decomposition rates compared with active layer soils. We examined active layer and permafrost soils near Fairbanks, AK, the Yukon River, and the Arctic Circle. Soils were incubated in the lab under aerobic and anaerobic conditions. Gas fluxes at -5 and 5 ??C were measured to calculate temperature response quotients (Q10). The Q10 was lower in permafrost soils (average 2.7) compared with active layer soils (average 7.5). Soil nutrients, leachable dissolved organic C (DOC) quality and quantity, and nuclear magnetic resonance spectroscopy of the soils revealed that the organic matter within permafrost soils is as labile, or even more so, than surface soils. Microbial abundances (fungi, bacteria, and subgroups: methanogens and Basidiomycetes) and exoenzyme activities involved in decomposition were lower in permafrost soils compared with active layer soils, which, together with the chemical data, supports the reduced Q10 values. CH4 fluxes were correlated with methanogen abundance and the highest CH4 production came from active layer soils. These results suggest that permafrost soils have high inherent decomposability, but low microbial abundances and activities reduce the temperature sensitivity of C fluxes. Despite these inherent limitations, however, respiration per unit soil C was higher in permafrost soils compared with active layer soils, suggesting that decomposition and heterotrophic respiration may contribute to a positive feedback to warming of this eco region. Published 2010. This article is a US Government work and is in the public domain in the

  1. Lake carbonate-δ 18O records from the Yukon Territory, Canada: Little Ice Age moisture variability and patterns

    NASA Astrophysics Data System (ADS)

    Anderson, Lesleigh; Finney, Bruce P.; Shapley, Mark D.

    2011-04-01

    A 1000-yr history of climate change in the central Yukon Territory, Canada, is inferred from sediment composition and isotope geochemistry from small, groundwater fed, Seven Mile Lake. Recent observations of lake-water δ 18O, lake level, river discharge, and climate variations, suggest that changes in regional effective moisture (precipitation minus evaporation) are reflected by the lake's hydrologic balance. The observations indicate that the lake is currently 18O-enriched by summer evaporation and that during years of increased precipitation, when groundwater inflow rates to the lake increase, lake-water δ 18O values decrease. Past lake-water δ 18O values are inferred from oxygen isotope ratios of fine-grained sedimentary endogenic carbonate. Variations in carbonate δ 18O, supplemented by those in carbonate and organic δ 13C, C/N ratios, and organic carbon, carbonate and biogenic silica accumulation rates, document changes in effective moisture at decadal time scales during the early Little Ice Age period to present. Results indicate that between ˜AD 1000 and 1600, effective moisture was higher than today. A shift to more arid climate conditions occurred after ˜AD 1650. The 19th and 20th centuries have been the driest of the past millennium. Temporal variations correspond with inferred shifts in summer evaporation from Marcella Lake δ 18O, a similarly small, stratified, alkaline lake located ˜250 km to the southwest, suggesting that the combined reconstructions accurately document the regional paleoclimate of the east-central interior. Comparison with regional glacial activity suggests differing regional moisture patterns during early and late Little Ice Age advances.

  2. Assessing Tinto's Model of Institutional Departure Using American Indian and Alaskan Native Longitudinal Data. ASHE Annual Meeting Paper.

    ERIC Educational Resources Information Center

    Pavel, D. Michael

    This paper on postsecondary outcomes illustrates a technique to determine whether or not mainstream models are appropriate for predicting educational outcomes of American Indians (AIs) and Alaskan Native (ANs). It introduces a prominent statistical procedure to assess models with empirical data and shows how the results can have implications for…

  3. Genetic characterization of Common Eiders breeding in the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Sonsthagen, Sarah A.; Talbot, Sandra L.; McCracken, Kevin G.

    2007-01-01

    We assessed population genetic subdivision among four colonies of Common Eiders (Somateria mollissima v-nigrum) breeding in the Yukon-Kuskokwim Delta (YKD), Alaska, using microsatellite genotypes and DNA sequences with differing modes of inheritance. Significant, albeit low, levels of genetic differentiation were observed between mainland populations and Kigigak Island for nuclear intron lamin A and mitochondrial DNA (mtDNA) control region. Intercolony variation in haplotypic frequencies also was observed at mtDNA. Positive growth signatures assayed from microsatellites, nuclear introns, and mtDNA indicate recent colonization of the YKD, and may explain the low levels of structuring observed. Gene flow estimates based on microsatellites, nuclear introns, and mtDNA suggest asymmetrical gene flow between mainland colonies and Kigigak Island, with more individuals on average dispersing from mainland populations to Kigigak Island than vice versa. The directionality of gene flow observed may be explained by the colonization of the YKD from northern glacial refugia or by YKD metapopulation dynamics.

  4. Nesting success of Northern Pintails on the coastal Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Grand, James B.

    1996-01-01

    We studied nesting chronology and success of Northern Pintails (Anas acuta) on the coastal Yukon-Kuskokwim Delta, Alaska during the summers of 1991-1993. We found a total of 795 nests during three annual searches of a 27.4 km2 area. Minimum nest density averaged 9.67 nests per km2. Nesting success varied among years and ranged from 43.12% in 1991 to 10.74% in 1993 (average 23.95%). Most nest loss was the result of predation and tidal flooding. Daily nest survival probability declined with nest initiation date in all three years and also varied with nest age in 1992. Clutch size averaged 7.63 ± 0.067 (SE) eggs per nest and was larger than reported for other populations of Northern Pintails. Clutch size declined during the 44-47 day nesting interval at a greater rate than reported for other populations of Northern Pintails. We conclude that sub-arctic and prairie nesting Northern Pintails have similar reproductive potentials.

  5. Densities of breeding birds and changes in vegetation in an alaskan boreal forest following a massive disturbance by spruce beetles

    USGS Publications Warehouse

    Matsuoka, S.M.; Handel, C.M.; Ruthrauff, D.R.

    2001-01-01

    We examined bird and plant communities among forest stands with different levels of spruce mortality following a large outbreak of spruce beetles (Dendroctonus rufipennis (Kirby)) in the Copper River Basin, Alaska. Spruce beetles avoided stands with black spruce (Picea mariana) and selectively killed larger diameter white spruce (Picea glauca), thereby altering forest structure and increasing the dominance of black spruce in the region. Alders (Alnus sp.) and crowberry (Empetrum nigrum) were more abundant in areas with heavy spruce mortality, possibly a response to the death of overstory spruce. Grasses and herbaceous plants did not proliferate as has been recorded following outbreaks in more coastal Alaskan forests. Two species closely tied to coniferous habitats, the tree-nesting Ruby-crowned Kinglet (Regulus calendula) and the red squirrel (Tamiasciurus hudsonicus), a major nest predator, were less abundant in forest stands with high spruce mortality than in low-mortality stands. Understory-nesting birds as a group were more abundant in forest stands with high levels of spruce mortality, although the response of individual bird species to tree mortality was variable. Birds breeding in stands with high spruce mortality likely benefited reproductively from lower squirrel densities and a greater abundance of shrubs to conceal nests from predators.

  6. Atmospheric methane sources - Alaskan tundra bogs, an alpine fen, and a subarctic boreal marsh

    NASA Technical Reports Server (NTRS)

    Sebacher, D. I.; Harriss, R. C.; Grice, S. S.; Bartlett, K. B.; Sebacher, S. M.

    1986-01-01

    Methane (CH4) flux measurements from Alaska tundra bogs, an alpine fen, and a subarctic boreal marsh were obtained at field sites ranging from Prudhoe Bay on the coast of the Arctic Ocean to the Alaskan Range south of Fairbanks during August 1984. In the tundra, average CH4 emission rates varied from 4.9 mg CH4 per sq m per day (moist tundra) to 119 mg CH4 per sq m per day (waterlogged tundra). Fluxes averaged 40 mg CH4 per sq m per day from wet tussock meadows in the Brooks Range and 289 mg Ch4 per sq m per day from an alpine fen in the Alaskan Range. The boreal marsh had an average CH4 emission rate of 106 mg CH4 per sq m per day. Significant emissions were detected in tundra areas where peat temperatures were as low as 4 C, and permafrost was only 25 cm below the ground surface. Emission rates from the 17 sites sampled were found to be logarithmically related to water levels at the sites. Extrapolation of the data to an estimate of the total annual CH4 emission from all arctic and boreal wetlands suggests that these ecosystems are a major source of atmospheric CH4 and could account for up to 23 percent of global CH4 emissions from wetlands.

  7. Significant Impact of Environment Regarding Eligibility of Native American and Alaskan Native Students for ESEA Title VII Regulations.

    ERIC Educational Resources Information Center

    Travis, Michael

    Early Russian religious and educational influences on the 20 various Alaskan Native languages are described, followed by those of American origin in schools and religious groups after the American purchase in 1867, all of which show the development of diglossia and language shifts. The present dual educational system, which includes state schools…

  8. Geology and assessment of undiscovered oil and gas resources of the Yukon Flats Basin Province, 2008

    USGS Publications Warehouse

    Bird, Kenneth J.; Stanley, Richard G.; Moore, Thomas E.; Gautier, Donald L.

    2017-12-22

    The hydrocarbon potential of the Yukon Flats Basin Province in Central Alaska was assessed in 2004 as part of an update to the National Oil and Gas Assessment. Three assessment units (AUs) were identified and assessed using a methodology somewhat different than that of the 2008 Circum-Arctic Resource Appraisal (CARA). An important difference in the methodology of the two assessments is that the 2004 assessment specified a minimum accumulation size of 0.5 million barrels of oil equivalent (MMBOE), whereas the 2008 CARA assessment specified a minimum size of 50 MMBOE. The 2004 assessment concluded that >95 percent of the estimated mean undiscovered oil and gas resources occur in a single AU, the Tertiary Sandstone AU. This is also the only AU of the three that extends north of the Arctic Circle.For the CARA project, the number of oil and gas accumulations in the 2004 assessment of the Tertiary Sandstone AU was re-evaluated in terms of the >50-MMBOE minimum accumulation size. By this analysis, and assuming the resource to be evenly distributed across the AU, 0.23 oil fields and 1.20 gas fields larger than 50 MMBOE are expected in the part of the AU north of the Arctic Circle. The geology suggests, however, that the area north of the Arctic Circle has a lower potential for oil and gas accumulations than the area to the south where the sedimentary section is thicker, larger volumes of hydrocarbons may have been generated, and potential structural traps are probably more abundant. Because of the low potential implied for the area of the AU north of the Arctic Circle, the Yukon Flats Tertiary Sandstone AU was not quantitatively assessed for the 2008 CARA.

  9. Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers

    USGS Publications Warehouse

    Raymond, P.A.; McClelland, J.W.; Holmes, R.M.; Zhulidov, A.V.; Mull, K.; Peterson, B.J.; Striegl, Robert G.; Aiken, G.R.; Gurtovaya, T.Y.

    2007-01-01

    The export and Δ14C-age of dissolved organic carbon (DOC) was determined for the Yenisey, Lena, Ob', Mackenzie, and Yukon rivers for 2004–2005. Concentrations of DOC elevate significantly with increasing discharge in these rivers, causing approximately 60% of the annual export to occur during a 2-month period following spring ice breakup. We present a total annual flux from the five rivers of ∼16 teragrams (Tg), and conservatively estimate that the total input of DOC to the Arctic Ocean is 25–36 Tg, which is ∼5–20% greater than previous fluxes. These fluxes are also ∼2.5× greater than temperate rivers with similar watershed sizes and water discharge. Δ14C-DOC shows a clear relationship with hydrology. A small pool of DOC slightly depleted in Δ14C is exported with base flow. The large pool exported with spring thaw is enriched in Δ14C with respect to current-day atmospheric Δ14C-CO2 values. A simple model predicts that ∼50% of DOC exported during the arctic spring thaw is 1–5 years old, ∼25% is 6–10 years in age, and 15% is 11–20 years old. The dominant spring melt period, a historically undersampled period, exports a large amount of young and presumably semilabile DOC to the Arctic Ocean.

  10. American Indian/Alaskan Native Undergraduate Retention at Predominantly White Institutions: An Elaboration of Tinto's Theory of College Student Departure

    ERIC Educational Resources Information Center

    Lee, Junghee; Donlan, William; Brown, Eddie F.

    2011-01-01

    This article reports findings from a major public university sponsored study undertaken with the intention of (a) improving university understanding of factors affecting American Indian/Alaskan Native (AI/AN) undergraduates' persistence at this institution, and (b) identifying in what areas, and in what manner, this institution could improve…

  11. Nature and origin of a Pleistocene-age massive ground-ice body exposed in the Chapman Lake moraine complex, central Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Lacelle, Denis; Lauriol, Bernard; Clark, Ian D.; Cardyn, Raphaelle; Zdanowicz, Christian

    2007-09-01

    A massive ground-ice body was found exposed in the headwall of a thaw flow developed within the Chapman Lake terminal moraine complex on the Blackstone Plateau (Ogilvie Mountains, central Yukon Territory), which is contemporaneous to the Reid glaciation. Based on visible cryostructures in the 4-m-high headwall, two units were identified: massive ground ice, overlain sharply by 2 m of icy diamicton. The nature and origin of the Chapman Lake massive ground ice was determined using cryostratigraphy, petrography, stable O-H isotopes and the molar concentration of occluded gases (CO 2, O 2, N 2 and Ar) entrapped in the ice, a new technique in the field of periglacial geomorphology that allows to distinguish between glacial and non-glacial intrasedimental ice. Collectively, the results indicate that the Chapman Lake massive ground ice formed by firn densification with limited melting-refreezing and underwent deformation near its margin. Given that the massive ground-ice body consists of relict glacier ice, it suggests that permafrost persisted, at least locally, on plateau areas in the central Yukon Territory since the middle Pleistocene. In addition, the d value of Chapman Lake relict glacier ice suggests that the ice covering the area during the Reid glaciation originated from a local alpine glaciation in the Ogilvie Mountains.

  12. Fire increases carbon fluxes from inland waters of the Yukon-Kuskokwim delta, Alaska.

    NASA Astrophysics Data System (ADS)

    Mann, P. J.; Bristol, E. M.; Dabrowski, J. S.; Jimmie, J. A.; Melton, S.; Navarro-Perez, E.; Peter, D. L.; Sae-lim, N.; Holmes, R. M.; Natali, S.; Schade, J. D.

    2017-12-01

    Climate change across high-latitude regions is expected to alter the hydrology and biogeochemistry of arctic environments, significantly impacting ecosystem C cycling and landscape scale C budgets. Fire represents one manifestation of arctic climate change with the number, extent and intensity of fires projected to increase over upcoming decades. The Yukon-Kuskokwim River Delta (YKD), Alaska, experienced unprecedented tundra fires in 2015 when more than 250 km2 underwent burn. In this study, we examined the effects of the 2015 YKD fire upon aquatic and terrestrial C fluxes, and investigated potential mechanisms causing changes to C-cycling. Field work was conducted during summer months (July-Sept) over two years, complimented with aerobic and anaerobic laboratory incubations. Burning of the terrestrial organic layer caused dramatic changes to soil moisture, the proportion of organic versus mineral soils near the land surface, and average active layer depth. Fire caused increased C fluxes (particularly CH4) from re-wet soils relative to unburnt soils, suggesting an interaction exists between fire history and soil moisture. Higher C fluxes from saturated ponds and fens across the landscape provided additional support for this theory. Pore-water chemistry in burnt catchments contained higher inorganic nutrient concentrations, specifically nitrogen, potentially driven by changing soil sorption processes and/ or infiltration rates. Organic matter delivery to inland waters within burns contained DOC of lower apparent molecular weight and aromaticity relative to unburnt waters (inferred from optical measures), and waters typically had higher temperatures, pH and dissolved mineral content. Lake and low-lying pond CO2 and CH4 emissions were consistently higher in burn catchment regions, with three to four-fold higher C emission rates. Our study indicates that fire may promote aquatic and terrestrial pathways for C loss and that these enhanced emissions may persist for years

  13. Social Disruption and Psychological Stress in an Alaskan Fishing Community: The Impact of the Exxon Valdez Oil Spill.

    ERIC Educational Resources Information Center

    Picou, J. Steven; And Others

    Technological accidents such as the Exxon Valdez oil spill in 1989 create man-made disaster situations that threaten community survival and the well-being and quality of life of community residents. This paper focuses on the social and psychological impact of the 1989 oil spill on Cordova, an isolated Alaskan community with high economic…

  14. Modelling guided waves in the Alaskan-Aleutian subduction zone

    NASA Astrophysics Data System (ADS)

    Coulson, Sophie; Garth, Thomas; Reitbrock, Andreas

    2016-04-01

    Subduction zone guided wave arrivals from intermediate depth earthquakes (70-300 km depth) have a huge potential to tell us about the velocity structure of the subducting oceanic crust as it dehydrates at these depths. We see guided waves as the oceanic crust has a slower seismic velocity than the surrounding material, and so high frequency energy is retained and delayed in the crustal material. Lower frequency energy is not retained in this crustal waveguide and so travels at faster velocities of the surrounding material. This gives a unique observation at the surface with low frequency energy arriving before the higher frequencies. We constrain this guided wave dispersion by comparing the waveforms recorded in real subduction zones with simulated waveforms, produced using finite difference full waveform modelling techniques. This method has been used to show that hydrated minerals in the oceanic crust persist to much greater depths than accepted thermal petrological subduction zone models would suggest in Northern Japan (Garth & Rietbrock, 2014a), and South America (Garth & Rietbrock, in prep). These observations also suggest that the subducting oceanic mantle may be highly hydrated at intermediate depth by dipping normal faults (Garth & Rietbrock 2014b). We use this guided wave analysis technique to constrain the velocity structure of the down going ~45 Ma Pacific plate beneath Alaska. Dispersion analysis is primarily carried out on guided wave arrivals recorded on the Alaskan regional seismic network. Earthquake locations from global earthquake catalogues (ISC and PDE) and regional earthquake locations from the AEIC (Alaskan Earthquake Information Centre) catalogue are used to constrain the slab geometry and to identify potentially dispersive events. Dispersed arrivals are seen at stations close to the trench, with high frequency (>2 Hz) arrivals delayed by 2 - 4 seconds. This dispersion is analysed to constrain the velocity and width of the proposed waveguide

  15. Arctic Oases? - River Aufeis Maintain Perennial Groundwater Habitat in the Arctic

    NASA Astrophysics Data System (ADS)

    Huryn, A. D.; Gooseff, M. N.; Briggs, M. A.; Terry, N.; Kendrick, M.; Hendrickson, P. J.; Grunewald, E. D.

    2017-12-01

    Aufeis are massive accumulations of ice found along many arctic rivers, with aufeis on some Alaskan rivers covering 20+ km2 and attaining thicknesses of 5+ m. Although aufeis are prominent landscape features, understanding of their ecology is poor. We propose that aufeis function as summer oases by providing meltwater and nutrients to downstream habitats and winter oases due to insulating layers of ice that maintain below-ground freshwater habitat that would otherwise be frozen in regions of continuous permafrost. To gain information about the ecological roles of aufeis, we installed 50 1-m deep wells in a 1.5 km2aufeis field along the Kuparuk River, an arctic tundra river in Alaska. We assessed the predictions that aufeis provide perennially-unfrozen, below-ground habitat for a specialized invertebrate community while functioning as hot spots for nutrient regeneration. Surface geophysical measurements made during the time of maximum ice thickness in 2017 indicated most of the Kuparuk feature was underlain by several meters of shallow frozen cobbles that were further underlain by a 10 m thick+ zone of thawed material. Ground penetrating radar and surface nuclear magnetic resonance data indicated several spatially-discrete thawed preferential flow zones through the shallow frozen sediment layer that may result from groundwater upwelling observed flowing through fractures in the icepack. Freshwater invertebrates sampled from the wells represent a rich community consisting of flatworms, annelids, copepods, ostracods, chironomids (Krenosmittia, Trichotanypus) and stoneflies. Although the potential for below-ground NH4+ and NO3-regeneration was indicated, analyses were complicated bya surprisingly strong and dynamic coupling of surface and below-ground water.

  16. Seasonal occurrence of migrant whimbrels and bristle-thighed curlews on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Handel, Colleen M.; Dau, Christian P.

    1988-01-01

    Migrant Whimbrels (Numenius phaeopus) and Bristle-thighed Curlews (N. tahitiensis) were recorded during five summers along coastal tundra of the Yukon-Kuskokwim Delta, Alaska. From June to September, 1975-1979, 358 flocks totalling 1,265 curlews were observed; an additional 54 flocks were identified by vocalization alone. Among the 359 flocks identified to species, 52% were of Whimbrels, 47% were of Bristle-thighed Curlews, and 1% were of both species. Flocks as large as 48 Whimbrels and 33 Bristle-thighed Curlews were recorded, but 87% of the flocks contained five or fewer birds. During 2 years with early springs a few Whimbrels and Bristle-thighed Curlews were recorded on the delta in early June; these may have been late spring migrants, oversummering nonbreeders, or very early failed breeders. Whimbrel numbers peaked twice each summer, first in middle to late July and again in late August. These peaks probably consisted mainly of late failed breeders and of successful breeders with juveniles, respectively. The patterns of occurrence of Bristle-thighed Curlews were more complex, with up to three peaks in abundance each season, probably consisting of the following populational subclasses: (1) early failed breeders from late June to mid-July, (2) late failed breeders in late July, and (3) successful breeders and juveniles in early August. Most Bristle-thighed Curlews were gone by mid-August and Whimbrels, by early September. For both species the earliest juveniles were seen in late July in flocks with adults. The Yukon-Kuskokwim Delta is conservatively estimated to support several thousands of both Whimbrels and Bristle-thighed Curlews. This area is considered to be particularly important for Bristle-thighed Curlews because it is the primary of only two known areas used during migration between their nesting grounds in Alaska and the first known stop on their wintering grounds in the Hawaiian Island chain, a transoceanic distance of 3,800 km. Whimbrels are more

  17. Timber harvest in interior Alaska.

    Treesearch

    Tricia L. Wurtz; Robert A. Ott; John C. Maisch

    2006-01-01

    The most active period of timber harvesting in the history of Alaska's interior occurred nearly a century ago (Roessler 1997). The beginning of this era was the year 1869, when steam-powered, stern-wheeled riverboats first operated on the Yukon River (Robe 1943). Gold was discovered in Alaska in the 40-Mile River area in 1886, a find that was overshadowed 10 years...

  18. Tintina Gold Province Study, Alaska and Yukon Territory, 2002-2007

    USGS Publications Warehouse

    Gough, Larry P.; Day, Warren C.

    2007-01-01

    The Tintina gold province is an arc-shaped 2,000-kilometer-long metallogenic province that extends from northern British Columbia, through the Yukon Territory, and across and into southwestern Alaska. In the United States, the province remains a prime area for gold exploration and includes such large gold deposits as Pogo, Fort Knox-True North, and Donlin Creek. In recent years, gold exploration and development and mining activity have accelerated in the area. Plans have been discussed for public and private projects and infrastructures associated with development. A U.S. Geological Survey study undertaken from 2002 to 2007 provides a context for understanding why and how the mineral resources of the area were formed, why this area is so abundantly endowed, and how the environmental signatures that are characteristic of the area are related to the development of mineral resources. Characterization of natural baseline metal concentrations in the area's watersheds is necessary to address future land-use issues related to mining and/or infrastructure activities. A thorough understanding of water-rock and element-bioavailability processes will help predict the possible environmental impact of development. The five tasks of this study add to the science of defining and understanding an 'intrusion-related gold system.'

  19. Pattern-process interactions at alpine treeline in southwest Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Danby, R.

    2011-12-01

    Results from an ensemble of studies conduced in southwest Yukon have uncovered a distinct "top-down/bottom-up" interaction at alpine treeline whereby terrain-induced gradients of solar radiation result in fundamental differences in plant-scale biological processes which, in turn, structure vegetation pattern at the landscape scale. Varied insolation creates differences in snow depth and timing of melt, soil temperature, and permafrost on opposing slopes that result in distinct physiological differences in white spruce (Picea glauca), the dominant treeline conifer. Measurement of young individuals indicated that secondary growth and lateral growth was significantly greater on south-facing slopes. Photosynthetic efficiency was reduced in individuals on south-facing slopes, while over-winter damage and mortality was significantly greater. Population-level processes also differed. Dendroecology and repeat photography indicated that treeline advanced on south-facing slopes during the 20th century, but that range expansion was limited on north-facing slopes. These process-related differences appear to be the mechanism for differences in treeline pattern at the landscape scale, including a higher treeline elevation and greater clustering of individuals on south-facing slopes. These results can be used to inform theory on the functional causation of treeline, rationalize differential treeline dynamics observed worldwide, and better inform predictions of future treeline dynamics.

  20. Dawson, Canada

    NASA Image and Video Library

    2012-07-09

    NASA Terra spacecraft acquired this image of Dawson, Canada. A boom town in 1898, discovery of gold in the Klondike fueled the massive influx of miners, merchants, and other support professions to this town on the Yukon River.

  1. Palaeohydrology of the Southwest Yukon Territory, Canada, based on multiproxy analyses of lake sediment cores from a depth transect

    USGS Publications Warehouse

    Anderson, L.; Abbott, M.B.; Finney, B.P.; Edwards, M.E.

    2005-01-01

    Lake-level variations at Marcella Lake, a small, hydrologically closed lake in the southwestern Yukon Territory, document changes in effective moisture since the early Holocene. Former water levels, driven by regional palaeohydrology, were reconstructed by multiproxy analyses of sediment cores from four sites spanning shallow to deep water. Marcella Lake today is thermally stratified, being protected from wind by its position in a depression. It is alkaline and undergoes bio-induced calcification. Relative accumulations of calcium carbonate and organic matter at the sediment-water interface depend on the location of the depositional site relative to the thermocline. We relate lake-level fluctuations to down-core stratigraphic variations in composition, geochemistry, sedimentary structures and to the occurrence of unconformities in four cores based on observations of modern limnology and sedimentation processes. Twenty-four AMS radiocarbon dates on macrofossils and pollen provide the lake-level chronology. Prior to 10 000 cal. BP water levels were low, but then they rose to 3 to 4 m below modern levels. Between 7500 and 5000 cal. BP water levels were 5 to 6 m below modern but rose by 4000 cal. BP. Between 4000 and 2000 cal. BP they were higher than modern. During the last 2000 years, water levels were either near or 1 to 2 m below modern levels. Marcella Lake water-level fluctuations correspond with previously documented palaeoenvironmental and palaeoclimatic changes and provide new, independent effective moisture information. The improved geochronology and quantitative water-level estimates are a framework for more detailed studies in the southwest Yukon. ?? 2005 Edward Arnold (Publishers) Ltd.

  2. A Formal Messaging Notation for Alaskan Aviation Data

    NASA Technical Reports Server (NTRS)

    Rios, Joseph L.

    2015-01-01

    Data exchange is an increasingly important aspect of the National Airspace System. While many data communication channels have become more capable of sending and receiving data at higher throughput rates, there is still a need to use communication channels efficiently with limited throughput. The limitation can be based on technological issues, financial considerations, or both. This paper provides a complete description of several important aviation weather data in Abstract Syntax Notation format. By doing so, data providers can take advantage of Abstract Syntax Notation's ability to encode data in a highly compressed format. When data such as pilot weather reports, surface weather observations, and various weather predictions are compressed in such a manner, it allows for the efficient use of throughput-limited communication channels. This paper provides details on the Abstract Syntax Notation One (ASN.1) implementation for Alaskan aviation data, and demonstrates its use on real-world aviation weather data samples as Alaska has sparse terrestrial data infrastructure and data are often sent via relatively costly satellite channels.

  3. Emissions of biogenic sulfur gases from Alaskan tundra

    NASA Technical Reports Server (NTRS)

    Hines, Mark E.; Morrison, Michael C.

    1992-01-01

    Results of sulfur emission measurements made in freshwater and marine wetlands in Alaskan tundra during the Arctic Boundary Layer Expedition 2A (ABLE 3A) in July 1988 are presented. The data indicate that this type of tundra emits very small amounts of gaseous sulfur and, when extrapolated globally, accounts for a very small percentage of the global flux of biogenic sulfur to the atmosphere. Sulfur emissions from marine sites are up to 20-fold greater than fluxes from freshwater habitats and are dominated by dimethyl sulfide (DMS). Highest emissions, with a mean of 6.0 nmol/sq m/h, occurred in water-saturated wet meadow areas. In drier upland tundra sites, highest fluxes occurred in areas inhabited by mixed vegetation and labrador tea at 3.0 nmol/sq m/h and lowest fluxes were from lichen-dominated areas at 0.9 nmol/sq m/h. DMS was the dominant gas emitted from all these sites. Emissions of DMS were highest from intertidal soils inhabited by Carex subspathacea.

  4. Landscape Hazards in Yukon Communities: Geological Mapping for Climate Change Adaptation Planning

    NASA Astrophysics Data System (ADS)

    Kennedy, K.; Kinnear, L.

    2010-12-01

    Climate change is considered to be a significant challenge for northern communities where the effects of increased temperature and climate variability are beginning to affect infrastructure and livelihoods (Arctic Climate Impact Assessment, 2004). Planning for and adapting to ongoing and future changes in climate will require the identification and characterization of social, economic, cultural, political and biophysical vulnerabilities. This pilot project addresses physical landscape vulnerabilities in two communities in the Yukon Territory through community-scale landscape hazard mapping and focused investigations of community permafrost conditions. Landscape hazards are identified by combining pre-existing data from public utilities and private-sector consultants with new geophysical techniques (ground penetrating radar and electrical resistivity), shallow drilling, surficial geological mapping, and permafrost characterization. Existing landscape vulnerabilities are evaluated based on their potential for hazard (low, medium or high) under current climate conditions, as well as under future climate scenarios. Detailed hazard maps and landscape characterizations for both communities will contribute to overall adaptation plans and allow for informed development, planning and mitigation of potentially threatening hazards in and around the communities.

  5. Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

    USGS Publications Warehouse

    Ball, Lyndsay B.; Smith, Bruce D.; Minsley, Burke J.; Abraham, Jared D.; Voss, Clifford I.; Astley, Beth N.; Deszcz-Pan, Maria; Cannia, James C.

    2011-01-01

    In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

  6. Residual Hydrochloride - Silicate Melt Associated With the Platinum-bearing Alaskan-type Galmoenan Intrusion (Koryak Highland, Russia)

    NASA Astrophysics Data System (ADS)

    Batanova, V.; Kamenetsky, D.; Pertsev, A.; Sobolev, A.

    2005-12-01

    Alaskan-type mafic-ultramafic complexes formed in subduction-related environments are considered to be a major source of platinum placer deposits [1]. A specific feature of these deposits is the dominant occurrence of Pt-Fe alloys (mainly isoferroplatinum) among PGE-bearing minerals [e.g. 2]. The PGE mineralization can be related to the high activity of chlorine in the parental magmas of Alaskan-type intrusions [3] and the potential of saline fluids to dissolve and transport Pt [4,5,6]. Fluxing of a refractory mantle wedge in a supra-subduction zone by chlorine-rich aqueous fluids was considered primarily responsible for the formation of PGE-enriched parental magmas [3]. Potential role of the saline magmatic fluids is further tackled by this study of melt/fluid inclusions in olivine from the Galmoenan pluton belonging to the Alaskan-type intrusive complex in the Kamchatka-Koryak province [7] and spatially associated with one of the most significant platinum placer deposits in Russia [8]. High-magnesian olivine (Fo 90.8) from the Galmoenan dunites hosts abundant hydrosaline chloride and hydrosaline chloride-silicate melt inclusions (5-30mkm). Inclusions trail fractures confined to individual olivine grains, and thus formed before re-crystallization completed. Heating stage experiments at 1 atm showed early melting within the inclusions at ~350C, however complete melting and homogenization was hampered by decrepitation at 650-750C. This suggests elevated pressures of trapping, at least 3-4 kb. The study of phase and chemical compositions of these inclusions by an electron probe, laser ablation ICP-MS and SIMS ion probe showed chlorides of Na, K, Ca, Fe and Ba, Fe-Cu-Ni sulfides and diopside among daughter phases; 2) high H2O abundances; 3) high abundances of alkali and alkali-earth elements (Na, K, Rb, Sr, Ba, Ca) and metals (Fe, Mn, Pb, Ni, Cu, Zn). Such compositions confirm the presence of metal-enriched hydrosaline melt at the latest stages of formation of the Pt

  7. Lithospheric Structure across the Alaskan Cordillera from Surface Waves and Receiver Functions

    NASA Astrophysics Data System (ADS)

    Ward, K. M.; Lin, F. C.

    2017-12-01

    The long awaited Transportable Array (TA) deployment in Alaska and western Canada is nearing its final deployment stage. With only one more deployment season, most of the TA station locations have been occupied and begun providing data. These TA stations combined with upgraded existing locations have provided enough high-quality data to begin investigating the crustal and upper mantle structure across the entire Alaskan Cordillera. From a tectonic standpoint, many interesting questions remain unanswered. For example, how does the transition from oceanic-oceanic subduction to continental-oceanic normal subduction to continental-oceanic "flat-slab" subduction to strike-slip conservative plate motion affect the deformation/uplift of the overriding plate and mantle geodynamic characteristics? How does the long and completed terrene accretion process partition stress/strain in the crust? On more local scales, are there any significant mid-crustal magmatic systems as observed in other sections of the American Cordillera, and if so, what is there role in uplift and crustal deformation? Our approach to investigating these questions is though surface wave imaging from ambient noise and earthquake generated sources along with Rayleigh wave ellipticity paired with Ps receiver functions. Our preliminary tomography results agree with previous studies but expand the spatial coverage showing additional detail. Our ellipticity results show a heterogeneous but spatially consistent anisotropic shallow crust. Although the complete TA data set has not yet been collected, we have jointly inverted surface waves with receiver functions for a 3-D shear-wave velocity model across the entire Alaskan Cordillera. Key features of our velocity model include a high-velocity feature in the upper mantle associated with the subducting Pacific plate that extends north of the seismicity used to contour the geometry of the slab and mid-crustal low-velocity zones associated with the active volcanics in

  8. Extending airborne electromagnetic surveys for regional active layer and permafrost mapping with remote sensing and ancillary data, Yukon Flats ecoregion, central Alaska

    USGS Publications Warehouse

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Minsley, Burke J.; Ji, Lei; Walvoord, Michelle Ann; Smith, Bruce D.; Abraham, Jared D.; Rose, Joshua R.

    2013-01-01

    Machine-learning regression tree models were used to extrapolate airborne electromagnetic resistivity data collected along flight lines in the Yukon Flats Ecoregion, central Alaska, for regional mapping of permafrost. This method of extrapolation (r = 0.86) used subsurface resistivity, Landsat Thematic Mapper (TM) at-sensor reflectance, thermal, TM-derived spectral indices, digital elevation models and other relevant spatial data to estimate near-surface (0–2.6-m depth) resistivity at 30-m resolution. A piecewise regression model (r = 0.82) and a presence/absence decision tree classification (accuracy of 87%) were used to estimate active-layer thickness (ALT) (< 101 cm) and the probability of near-surface (up to 123-cm depth) permafrost occurrence from field data, modelled near-surface (0–2.6 m) resistivity, and other relevant remote sensing and map data. At site scale, the predicted ALTs were similar to those previously observed for different vegetation types. At the landscape scale, the predicted ALTs tended to be thinner on higher-elevation loess deposits than on low-lying alluvial and sand sheet deposits of the Yukon Flats. The ALT and permafrost maps provide a baseline for future permafrost monitoring, serve as inputs for modelling hydrological and carbon cycles at local to regional scales, and offer insight into the ALT response to fire and thaw processes.

  9. Seismic array processing and computational infrastructure for improved monitoring of Alaskan and Aleutian seismicity and volcanoes

    NASA Astrophysics Data System (ADS)

    Lindquist, Kent Gordon

    We constructed a near-real-time system, called Iceworm, to automate seismic data collection, processing, storage, and distribution at the Alaska Earthquake Information Center (AEIC). Phase-picking, phase association, and interprocess communication components come from Earthworm (U.S. Geological Survey). A new generic, internal format for digital data supports unified handling of data from diverse sources. A new infrastructure for applying processing algorithms to near-real-time data streams supports automated information extraction from seismic wavefields. Integration of Datascope (U. of Colorado) provides relational database management of all automated measurements, parametric information for located hypocenters, and waveform data from Iceworm. Data from 1997 yield 329 earthquakes located by both Iceworm and the AEIC. Of these, 203 have location residuals under 22 km, sufficient for hazard response. Regionalized inversions for local magnitude in Alaska yield Msb{L} calibration curves (logAsb0) that differ from the Californian Richter magnitude. The new curve is 0.2\\ Msb{L} units more attenuative than the Californian curve at 400 km for earthquakes north of the Denali fault. South of the fault, and for a region north of Cook Inlet, the difference is 0.4\\ Msb{L}. A curve for deep events differs by 0.6\\ Msb{L} at 650 km. We expand geographic coverage of Alaskan regional seismic monitoring to the Aleutians, the Bering Sea, and the entire Arctic by initiating the processing of four short-period, Alaskan seismic arrays. To show the array stations' sensitivity, we detect and locate two microearthquakes that were missed by the AEIC. An empirical study of the location sensitivity of the arrays predicts improvements over the Alaskan regional network that are shown as map-view contour plots. We verify these predictions by detecting an Msb{L} 3.2 event near Unimak Island with one array. The detection and location of four representative earthquakes illustrates the expansion

  10. Use of fish hydrolysates and fishmeal by-products of the Alaskan fishing industry in diets for Pacific white shrimp (Litopenaeus vannamei)

    USDA-ARS?s Scientific Manuscript database

    The suitability of four fish hydrolysates and two fishmeals derived from by-products of the Alaskan fishing industry, as menhaden fishmeal replacements in shrimp diets was determined. A control diet (30% crude protein and 8.5% crude lipid) was produced with menhaden meal (13% of diet). Experimental ...

  11. Remote measurement of surface-water velocity using infrared videography and PIV: a proof-of-concept for Alaskan rivers

    USGS Publications Warehouse

    Kinzel, Paul J.; Legleiter, Carl; Nelson, Jonathan M.; Conaway, Jeffrey S.

    2017-01-01

    Thermal cameras with high sensitivity to medium and long wavelengths can resolve features at the surface of flowing water arising from turbulent mixing. Images acquired by these cameras can be processed with particle image velocimetry (PIV) to compute surface velocities based on the displacement of thermal features as they advect with the flow. We conducted a series of field measurements to test this methodology for remote sensing of surface velocities in rivers. We positioned an infrared video camera at multiple stations across bridges that spanned five rivers in Alaska. Simultaneous non-contact measurements of surface velocity were collected with a radar gun. In situ velocity profiles were collected with Acoustic Doppler Current Profilers (ADCP). Infrared image time series were collected at a frequency of 10Hz for a one-minute duration at a number of stations spaced across each bridge. Commercial PIV software used a cross-correlation algorithm to calculate pixel displacements between successive frames, which were then scaled to produce surface velocities. A blanking distance below the ADCP prevents a direct measurement of the surface velocity. However, we estimated surface velocity from the ADCP measurements using a program that normalizes each ADCP transect and combines those normalized transects to compute a mean measurement profile. The program can fit a power law to the profile and in so doing provides a velocity index, the ratio between the depth-averaged and surface velocity. For the rivers in this study, the velocity index ranged from 0.82 – 0.92. Average radar and extrapolated ADCP surface velocities were in good agreement with average infrared PIV calculations.

  12. On the Frontline: Tracking Ocean Acidification in an Alaskan Shellfish Hatchery

    PubMed Central

    Evans, Wiley; Mathis, Jeremy T.; Ramsay, Jacqueline; Hetrick, Jeff

    2015-01-01

    The invasion of anthropogenic carbon dioxide (CO2) into the ocean is shifting the marine carbonate system such that saturation states of calcium carbonate (CaCO3) minerals are decreasing, and this is having a detrimental impact on early life stages of select shellfish species. The global, secular decrease in CaCO3 saturation states is occurring on top of a backdrop of large natural variability in coastal settings; progressively shifting the envelope of variability and leading to longer and more frequent exposure to adverse conditions. This is a great concern in the State of Alaska, a high-latitude setting vulnerable to rapid changes in the marine carbonate system, where an emerging shellfish industry plans major growth over the coming decades. Currently, the Alutiiq Pride Shellfish Hatchery (APSH) in Seward, Alaska is the only hatchery in the state, and produces many shellfish species with early life stages known to be sensitive to low CaCO3 saturation states. Here we present the first land-based OA measurements made in an Alaskan shellfish hatchery, and detail the trends in the saturation state of aragonite (Ωarag), the more soluble form of CaCO3, over a 10-month period in the APSH seawater supply. These data indicate the largest changes are on the seasonal time scale, with extended periods of sub-optimal Ωarag levels (Ωarag < 1.5) in winter and autumn associated with elevated water column respiration and short-lived runoff events, respectively. The data pinpoint a 5-month window of reprieve with favorable Ωarag conditions above the sub-optimal Ωarag threshold, which under predicted upper-bound CO2 emissions trajectories is estimated to close by 2040. To date, many species in production at APSH remain untested in their response to OA, and the data presented here establish the current conditions at APSH as well as provide a framework for hatchery-based measurements in Alaska. The current and expected conditions seen at APSH are essential to consider for this

  13. Leaders' perspectives in the Yellowstone to Yukon Conservation Initiative

    USGS Publications Warehouse

    Mattson, D.J.; Clark, S.G.; Byrd, K.L.; Brown, S.R.; Robinson, B.

    2011-01-01

    The Yellowstone to Yukon Conservation Initiative (Y2Y) was created in 1993 to advance conservation in a 1.2 million km2 portion of the North American Rocky Mountains. We assembled 21 people with influence over Y2Y in a workshop to elucidate perspectives on challenges and solutions for this organization at a key point in its evolution, and used Q method to define four perspectives on challenges and three on solutions. Participants were differentiated by four models for effecting change-vision-based advocacy, practice-based learning, political engagement, and scientific management-with emphasis on the first three. Those with authority in Y2Y aligned with vision-based advocacy and expressed ambivalence about practice-based adaptive learning and rigorous appraisals of existing strategies. Workshop results were consistent with an apparent trend toward organizational maturation focused on stabilizing revenues, developing formal organizational arrangements, and focusing strategies. Consolidation of power in Y2Y around a long-standing formula does not bode well for the effectiveness of Y2Y. We recommend that leaders in Y2Y and similar organizations focused on large-scale conservation to create and maintain an open system-philosophically and operationally-that capitalizes on the diverse perspectives and skills of individuals who are attracted to such efforts. We also recommend that the Y2Y initiative be followed closely to harvest additional lessons for potential application to large-scale conservation efforts elsewhere. ?? Springer Science+Business Media, LLC(outside the USA).2011.

  14. Anti-infective discorhabdins from a deep-water alaskan sponge of the genus Latrunculia.

    PubMed

    Na, Minkyun; Ding, Yuanqing; Wang, Bin; Tekwani, Babu L; Schinazi, Raymond F; Franzblau, Scott; Kelly, Michelle; Stone, Robert; Li, Xing-Cong; Ferreira, Daneel; Hamann, Mark T

    2010-03-26

    Bioassay- and LC-MS-guided fractionation of a methanol extract from a new deep-water Alaskan sponge species of the genus Latrunculia resulted in the isolation of two new brominated pyrroloiminoquinones, dihydrodiscorhabdin B and discorhabdin Y (2), along with six known pyrroloiminoquinone alkaloids, discorhabdins A (3), C (4), E (5), and L (6), dihydrodiscorhabdin C (7), and the benzene derivative 8. Compounds 3, 4, and 7 exhibited anti-HCV activity, antimalarial activity, and selective antimicrobial activity. Although compounds 3 and 7 displayed potent and selective in vitro antiprotozoal activity, Plasmodium berghei-infected mice did not respond to these metabolites due to their toxicity in vivo.

  15. Anti-infective Discorhabdins from a Deep-Water Alaskan Sponge of the Genus Latrunculia†

    PubMed Central

    Na, MinKyun; Ding, Yuanqing; Wang, Bin; Tekwani, Babu L.; Schinazi, Raymond F.; Franzblau, Scott; Kelly, Michelle; Stone, Robert; Li, Xing-Cong; Ferreira, Daneel; Hamann, Mark T.

    2016-01-01

    Bioassay- and LC-MS-guided fractionation of a methanol extract from a new deep-water Alaskan sponge species of the genus Latrunculia resulted in the isolation of two new brominated pyrroloiminoquinones, dihydrodiscorhabdin B (1) and discorhabdin Y (2), along with six known pyrroloiminoquinone alkaloids, discorhabdins A (3), C (4), E (5), and L (6), dihydrodiscorhabdin C (7), and the benzene derivative 8. Compounds 3, 4, and 7 exhibited anti-HCV activity, antimalarial activity, and selective antimicrobial activity. Although compounds 3 and 7 displayed potent and selective in vitro antiprotozoal activity, Plasmodium berghei-infected mice did not respond to these metabolites due to their toxicity in vivo. PMID:20337497

  16. A New Wave of Permafrost Warming in the Alaskan Interior?

    NASA Astrophysics Data System (ADS)

    Romanovsky, V. E.; Nicolsky, D.; Cable, W.; Kholodov, A. L.; Panda, S. K.

    2017-12-01

    The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Ground temperatures are a primary indicator of permafrost stability. Many of the research sites in our permafrost network are located along the North American Arctic Permafrost-Ecological Transect that spans all permafrost zones in Alaska. Most of the sites in Alaska show substantial warming of permafrost since the 1980s. The magnitude of warming has varied with location, but was typically from 0.5 to 3°C. However, this warming was not linear in time and not spatially uniform. In some regions this warming even may be reversed and a slight recent cooling of permafrost has been observed recently at some locations. The Interior of Alaska is one of such regions where a slight permafrost cooling was observed starting in the late 1990s that has continued through the 2000s and in the beginning of the 2010s. The cooling has followed the substantial increase in permafrost temperatures documented for the Interior during the 1980s and 1990s. Permafrost temperatures at 15 m depth increased here by 0.3 to 0.6°C between 1983 and 1996. In most locations they reached their maximum in the second half of the 1990s. Since then, the permafrost temperatures started to decrease slowly and by 2013 this decrease at some locations was as much as 0.3°C at 15 m depth. There are some indications that the warming trend in the Alaskan Interior permafrost resumed during the last four years. By 2016, new record highs for the entire period of measurements of permafrost temperatures at 15 m depth were recorded at several locations. The latest observed permafrost warming in the Interior was combined with higher than normal summer precipitations. This combination has triggered near-surface permafrost degradation in many locations with adverse consequences for the ground surface stability affecting ecosystems and infrastructure. In

  17. The effects of fire on greenhouse gas fluxes from mosses and lichen patches in the Yukon Kuskokwim Delta, AK.

    NASA Astrophysics Data System (ADS)

    Navarro-Perez, E.; Natali, S.; Schade, J. D.; Holmes, R. M.; Mann, P. J.

    2017-12-01

    Climate change has altered patterns of temperature, emissions of greenhouse gases and increased fire frequencies, especially in the Artic. Until recently, the Arctic has been a carbon (C) sink, but have begun releasing C in recent years, likely in response to warming temperatures, permafrost thaw and resulting changes in microbial processes. In addition, increases in fire frequency and intensity are changing vegetation patterns, particularly the relative importance of mosses and lichens. These changes alter soil temperatures, nutrient availability, and moisture, consequently affecting microbial processes and the release of greenhouse gases (GHG) such as N2O, CO2 and CH4. The objective of this research was to understand how recent fires in the Yukon-Kuskokwim River Delta in southwest Alaska are affecting the emission of GHGs from peat plateau soils. We hypothesized that the presence of mosses and lichen would change soil moisture and temperature, leading to changes in GHG production after fire. We also hypothesized that fire would increase soil nutrient availability, which would increase microbial process rates and GHG emissions. To test these hypotheses, we measured N2O, CH4 and CO2 fluxes from moss and lichen patches in three burned and unburned areas and collected soil cores for analyses of gravimetric soil moisture, carbon and nitrogen concentrations, and N mineralization rates. Soil temperatures were measured in the field with a thermocouple. Results demonstrated low but measurable CH4 emissions from all patches, suggesting peat plateaus in the YK Delta may be CH4 sources. In addition, CO2 emissions were higher in soils under lichen patches in burned areas than unburned controls. Finally, results suggest that burned areas have higher concentrations of extractable NH4 and NO3, and that increased N may be increasing soil respiration.

  18. All-weather ice information system for Alaskan arctic coastal shipping

    NASA Technical Reports Server (NTRS)

    Gedney, R. T.; Jirberg, R. J.; Schertler, R. J.; Mueller, R. A.; Chase, T. L.; Kramarchuk, I.; Nagy, L. A.; Hanlon, R. A.; Mark, H.

    1977-01-01

    A near real-time ice information system designed to aid arctic coast shipping along the Alaskan North Slope is described. The system utilizes a X-band Side Looking Airborne Radar (SLAR) mounted aboard a U.S. Coast Guard HC-130B aircraft. Radar mapping procedures showing the type, areal distribution and concentration of ice cover were developed. In order to guide vessel operational movements, near real-time SLAR image data were transmitted directly from the SLAR aircraft to Barrow, Alaska and the U.S. Coast Guard icebreaker Glacier. In addition, SLAR image data were transmitted in real time to Cleveland, Ohio via the NOAA-GOES Satellite. Radar images developed in Cleveland were subsequently facsimile transmitted to the U.S. Navy's Fleet Weather Facility in Suitland, Maryland for use in ice forecasting and also as a demonstration back to Barrow via the Communications Technology Satellite.

  19. Comparative Analysis of Phenolic Content and Profile, Antioxidant Capacity and Anti-inflammatory Bioactivity in Wild Alaskan and Commercial Vaccinium Berries

    PubMed Central

    Grace, Mary H.; Esposito, Debora; Dunlap, Kriya L.; Lila, Mary Ann

    2014-01-01

    Wild Alaskan Vaccinium berries, V. vitis-idaea (lowbush cranberry) and V. uliginosum (bog blueberry), were investigated in parallel to their commercial berry counterparts; V. macrocarpon (cranberry) and V. angustifolium (lowbush blueberry). Lowbush cranberry accumulated about twice the total phenolics (624.4 mg/100 g FW) and proanthocyanidins (278.8 mg/100 g) content as commercial cranberries, but A-type proanthocyanidins were more prevalent in the latter. Bog blueberry anthocyanin and total phenolic contents of 220 and 504.5 mg/100 g, respectively, significantly exceeded those of the lowbush blueberry. Chlorogenic acid, however, was quite high in lowbush blueberry (83.1 mg/100 g), but undetected in bog blueberry, and the proanthocyanidins of lowbush blueberry had significantly higher levels of polymerization. Antioxidant capacity (DPPH, APTS and FRAP) correlated with phenolic content for each berry. A polyphenol-rich fraction from lowbush cranberry exhibited dose-dependent inhibition of LPS-elicited induction of IL-1β in RAW 264.7 cells, indicative of strong anti-inflammatory activity. These results corroborate the historic use of wild Alaskan berries as medicinally-important foods in Alaska Native communities. PMID:24219831

  20. Comparative analysis of phenolic content and profile, antioxidant capacity, and anti-inflammatory bioactivity in wild Alaskan and commercial Vaccinium berries.

    PubMed

    Grace, Mary H; Esposito, Debora; Dunlap, Kriya L; Lila, Mary Ann

    2014-05-07

    Wild Alaskan Vaccinium berries, V. vitis-idaea (lowbush cranberry) and V. uliginosum (bog blueberry), were investigated in parallel with their commercial berry counterparts, V. macrocarpon (cranberry) and V. angustifolium (lowbush blueberry). Lowbush cranberry accumulated about twice the total phenolics (624.4 mg/100 g FW) and proanthocyanidins (278.8 mg/100 g) content as commercial cranberries, but A-type proanthocyanidins were more prevalent in the latter. Bog blueberry anthocyanin and total phenolic contents of 220 and 504.5 mg/100 g, respectively, significantly exceeded those of the lowbush blueberry. Chlorogenic acid, however, was quite high in lowbush blueberry (83.1 mg/100 g), but undetected in bog blueberry, and the proanthocyanidins of lowbush blueberry had significantly higher levels of polymerization. Antioxidant capacity (DPPH, APTS, and FRAP) correlated with phenolic content for each berry. A polyphenol-rich fraction from lowbush cranberry exhibited dose-dependent inhibition of LPS-elicited induction of IL-1β in RAW 264.7 cells, indicative of strong anti-inflammatory activity. These results corroborate the historic use of wild Alaskan berries as medicinally important foods in Alaska Native communities.

  1. Isolation of a complete circular virus genome sequence from an Alaskan black-capped chickadee (Poecile atricapillus) gastrointestinal tract sample.

    USGS Publications Warehouse

    Hanna, Zachary R.; Runckel, Charles; Fuchs, Jerome; DeRisi, Joseph L.; Mindell, David P.; Van Hemert, Caroline R.; Handel, Colleen M.; Dumbacher, John P.

    2015-01-01

    We report here the genome sequence of a circular virus isolated from samples of an Alaskan black-capped chickadee (Poecile atricapillus) gastrointestinal tract. The genome is 2,152 bp in length and is most similar (30 to 44.5% amino acid identity) to the genome sequences of other single-stranded DNA (ssDNA) circular viruses belonging to the gemycircularvirus group.

  2. Modeling fire severity in black spruce stands in the Alaskan boreal forest using spectral and non-spectral geospatial data

    Treesearch

    K. Barrett; E.S. Kasischke; A.D. McGuire; M.R. Turetsky; E.S. Kane

    2010-01-01

    Biomass burning in the Alaskan interior is already a major disturbance and source of carbon emissions, and is likely to increase in response to the warming and drying predicted for the future climate. In addition to quantifying changes to the spatial and temporal patterns of burned areas, observing variations in severity is the key to studying the impact of changes to...

  3. Hydrology of two slopes in subarctic Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Carey, Sean K.; Woo, Ming-Ko

    1999-11-01

    Two subarctic forested slopes in central Wolf Creek basin, Yukon, were studied in 1996-1997 to determine the seasonal pattern of the hydrologic processes. A south-facing slope has a dense aspen forest on silty soils with seasonal frost only and a north-facing slope has open stands of black spruce and an organic layer on top of clay sediments with permafrost. Snowmelt is advanced by approximately one month on the south-facing slope due to greater radiation receipt. Meltwater infiltrates its seasonally frozen soil with low ice content, recharging the soil moisture reservoir but yielding no lateral surface or subsurface flow. Summer evaporation depletes this recharged moisture and any additional rainfall input, at the expense of surface or subsurface flow. The north-facing slope with an ice rich substrate hinders deep percolation. Snow meltwater is impounded within the organic layer to produce surface runoff in rills and gullies, and subsurface flow along pipes and within the matrix of the organic soil. During the summer, most subsurface flows are confined to the organic layer which has hydraulic conductivities orders of magnitudes larger than the underlying boulder-clay. Evaporation on the north-facing slope declines as both the frost table and the water table descend in the summer. A water balance of the two slopes demonstrates that vertical processes of infiltration and evaporation dominate moisture exchanges on the south-facing slope, whereas the retardation of deep drainage by frost and by clayey soil on the permafrost slope promotes a strong lateral flow component, principally within the organic layer. These results have the important implication that permafrost slopes and organic horizons are the principal controls on streamflow generation in subarctic catchments.

  4. Hydrology of the North Klondike River: carbon export, water balance and inter-annual climate influences within a sub-alpine permafrost catchment.

    PubMed

    Lapp, Anthony; Clark, Ian; Macumber, Andrew; Patterson, Tim

    2017-10-01

    Arctic and sub-arctic watersheds are undergoing significant changes due to recent climate warming and degrading permafrost, engendering enhanced monitoring of arctic rivers. Smaller catchments provide understanding of discharge, solute flux and groundwater recharge at the process level that contributes to an understanding of how larger arctic watersheds are responding to climate change. The North Klondike River, located in west central Yukon, is a sub-alpine permafrost catchment, which maintains an active hydrological monitoring station with a record of >40 years. In addition to being able to monitor intra-annual variability, this data set allows for more complex analysis of streamflow records. Streamflow data, geochemistry and stable isotope data for 2014 show a groundwater-dominated system, predominantly recharged during periods of snowmelt. Radiocarbon is shown to be a valuable tracer of soil zone recharge processes and carbon sources. Winter groundwater baseflow contributes 20 % of total annual discharge, and accounts for up to 50 % of total river discharge during the spring and summer months. Although total stream discharge remains unchanged, mean annual groundwater baseflow has increased over the 40-year monitoring period. Wavelet analysis reveals a catchment that responds to El Niño and longer solar cycles, as well as climatic shifts such as the Pacific Decadal Oscillation. Dedicated to Professor Peter Fritz on the occasion of his 80th birthday.

  5. Photointerpretation of Alaskan post-earthquake photography

    USGS Publications Warehouse

    Hackman, R.J.

    1965-01-01

    Aerial photographs taken after the March 27, 1964, Good Friday, Alaskan earthquake were examined stereoscopically to determine effects of the earthquake in areas remote from the towns, highways, and the railroad. The two thousand black and white photographs used in this study were taking in April, after the earthquake, by the U. S. Coast & Geodetic Survey and were generously supplied to the U. S. Geological Survey. Part of the photographs, at a scale of 1/24,000, provide blanket coverage of approximately 2,000 square miles of land area north and west of Prince William Sound, including parts of the mainland and some of the adjacent islands. The epicenter of the earthquake, near the head of Unakwik Inlet, is located in this area. The rest of the photographs, at scales ranging from 1/17,000 to 1/40,000, cover isolated strips of the coastline of the mainland and nearby islands in the general area of Prince William Sound. Figure 1 shows the area of new photo coverage used in this study. The objective of the study was to determine quickly whether geological features resulting from the earthquake, such as faults, changes in shoreline, cracks in surficial material, pressure ridges in lake ice, fractures in glaciers and lake ice, and rock slides and avalanches, might be identifiable by photointerpretation. The study was made without benefit of comparisons with older, or pre-earthquake photography, which was not readily available for immediate use.

  6. Temperature and injection water source influence microbial community structure in four Alaskan North Slope hydrocarbon reservoirs

    PubMed Central

    Piceno, Yvette M.; Reid, Francine C.; Tom, Lauren M.; Conrad, Mark E.; Bill, Markus; Hubbard, Christopher G.; Fouke, Bruce W.; Graff, Craig J.; Han, Jiabin; Stringfellow, William T.; Hanlon, Jeremy S.; Hu, Ping; Hazen, Terry C.; Andersen, Gary L.

    2014-01-01

    A fundamental knowledge of microbial community structure in petroleum reservoirs can improve predictive modeling of these environments. We used hydrocarbon profiles, stable isotopes, and high-density DNA microarray analysis to characterize microbial communities in produced water from four Alaskan North Slope hydrocarbon reservoirs. Produced fluids from Schrader Bluff (24–27°C), Kuparuk (47–70°C), Sag River (80°C), and Ivishak (80–83°C) reservoirs were collected, with paired soured/non-soured wells sampled from Kuparuk and Ivishak. Chemical and stable isotope data suggested Schrader Bluff had substantial biogenic methane, whereas methane was mostly thermogenic in deeper reservoirs. Acetoclastic methanogens (Methanosaeta) were most prominent in Schrader Bluff samples, and the combined δD and δ13C values of methane also indicated acetoclastic methanogenesis could be a primary route for biogenic methane. Conversely, hydrogenotrophic methanogens (e.g., Methanobacteriaceae) and sulfide-producing Archaeoglobus and Thermococcus were more prominent in Kuparuk samples. Sulfide-producing microbes were detected in all reservoirs, uncoupled from souring status (e.g., the non-soured Kuparuk samples had higher relative abundances of many sulfate-reducers compared to the soured sample, suggesting sulfate-reducers may be living fermentatively/syntrophically when sulfate is limited). Sulfate abundance via long-term seawater injection resulted in greater relative abundances of Desulfonauticus, Desulfomicrobium, and Desulfuromonas in the soured Ivishak well compared to the non-soured well. In the non-soured Ivishak sample, several taxa affiliated with Thermoanaerobacter and Halomonas predominated. Archaea were not detected in the deepest reservoirs. Functional group taxa differed in relative abundance among reservoirs, likely reflecting differing thermal and/or geochemical influences. PMID:25147549

  7. Inland waters and their role in the carbon cycle of Alaska

    USGS Publications Warehouse

    Stackpoole, Sarah M.; Butman, David E.; Clow, David W.; Verdin, Kristine L.; Gaglioti, Benjamin V.; Genet, Hélène; Striegl, Robert G.

    2017-01-01

    The magnitude of Alaska (AK) inland waters carbon (C) fluxes is likely to change in the future due to amplified climate warming impacts on the hydrology and biogeochemical processes in high latitude regions. Although current estimates of major aquatic C fluxes represent an essential baseline against which future change can be compared, a comprehensive assessment for AK has not yet been completed. To address this gap, we combined available data sets and applied consistent methodologies to estimate river lateral C export to the coast, river and lake carbon dioxide (CO2) and methane (CH4) emissions, and C burial in lakes for the six major hydrologic regions in the state. Estimated total aquatic C flux for AK was 41 Tg C/yr. Major components of this total flux, in Tg C/yr, were 18 for river lateral export, 17 for river CO2 emissions, and 8 for lake CO2 emissions. Lake C burial offset these fluxes by 2 Tg C/yr. River and lake CH4 emissions were 0.03 and 0.10 Tg C/yr, respectively. The Southeast and South central regions had the highest temperature, precipitation, terrestrial net primary productivity (NPP), and C yields (fluxes normalized to land area) were 77 and 42 g C·m−2·yr−1, respectively. Lake CO2 emissions represented over half of the total aquatic flux from the Southwest (37 g C·m−2·yr−1). The North Slope, Northwest, and Yukon regions had lesser yields (11, 15, and 17 g C·m2·yr−1), but these estimates may be the most vulnerable to future climate change, because of the heightened sensitivity of arctic and boreal ecosystems to intensified warming. Total aquatic C yield for AK was 27 g C·m−2·yr−1, which represented 16% of the estimated terrestrial NPP. Freshwater ecosystems represent a significant conduit for C loss, and a more comprehensive view of land-water-atmosphere interactions is necessary to predict future climate change impacts on the Alaskan ecosystem C balance.

  8. Single nucleotide polymorphisms unravel hierarchical divergence and signatures of selection among Alaskan sockeye salmon (Oncorhynchus nerka) populations.

    PubMed

    Gomez-Uchida, Daniel; Seeb, James E; Smith, Matt J; Habicht, Christopher; Quinn, Thomas P; Seeb, Lisa W

    2011-02-18

    Disentangling the roles of geography and ecology driving population divergence and distinguishing adaptive from neutral evolution at the molecular level have been common goals among evolutionary and conservation biologists. Using single nucleotide polymorphism (SNP) multilocus genotypes for 31 sockeye salmon (Oncorhynchus nerka) populations from the Kvichak River, Alaska, we assessed the relative roles of geography (discrete boundaries or continuous distance) and ecology (spawning habitat and timing) driving genetic divergence in this species at varying spatial scales within the drainage. We also evaluated two outlier detection methods to characterize candidate SNPs responding to environmental selection, emphasizing which mechanism(s) may maintain the genetic variation of outlier loci. For the entire drainage, Mantel tests suggested a greater role of geographic distance on population divergence than differences in spawn timing when each variable was correlated with pairwise genetic distances. Clustering and hierarchical analyses of molecular variance indicated that the largest genetic differentiation occurred between populations from distinct lakes or subdrainages. Within one population-rich lake, however, Mantel tests suggested a greater role of spawn timing than geographic distance on population divergence when each variable was correlated with pairwise genetic distances. Variable spawn timing among populations was linked to specific spawning habitats as revealed by principal coordinate analyses. We additionally identified two outlier SNPs located in the major histocompatibility complex (MHC) class II that appeared robust to violations of demographic assumptions from an initial pool of eight candidates for selection. First, our results suggest that geography and ecology have influenced genetic divergence between Alaskan sockeye salmon populations in a hierarchical manner depending on the spatial scale. Second, we found consistent evidence for diversifying

  9. Single nucleotide polymorphisms unravel hierarchical divergence and signatures of selection among Alaskan sockeye salmon (Oncorhynchus nerka) populations

    PubMed Central

    2011-01-01

    Background Disentangling the roles of geography and ecology driving population divergence and distinguishing adaptive from neutral evolution at the molecular level have been common goals among evolutionary and conservation biologists. Using single nucleotide polymorphism (SNP) multilocus genotypes for 31 sockeye salmon (Oncorhynchus nerka) populations from the Kvichak River, Alaska, we assessed the relative roles of geography (discrete boundaries or continuous distance) and ecology (spawning habitat and timing) driving genetic divergence in this species at varying spatial scales within the drainage. We also evaluated two outlier detection methods to characterize candidate SNPs responding to environmental selection, emphasizing which mechanism(s) may maintain the genetic variation of outlier loci. Results For the entire drainage, Mantel tests suggested a greater role of geographic distance on population divergence than differences in spawn timing when each variable was correlated with pairwise genetic distances. Clustering and hierarchical analyses of molecular variance indicated that the largest genetic differentiation occurred between populations from distinct lakes or subdrainages. Within one population-rich lake, however, Mantel tests suggested a greater role of spawn timing than geographic distance on population divergence when each variable was correlated with pairwise genetic distances. Variable spawn timing among populations was linked to specific spawning habitats as revealed by principal coordinate analyses. We additionally identified two outlier SNPs located in the major histocompatibility complex (MHC) class II that appeared robust to violations of demographic assumptions from an initial pool of eight candidates for selection. Conclusions First, our results suggest that geography and ecology have influenced genetic divergence between Alaskan sockeye salmon populations in a hierarchical manner depending on the spatial scale. Second, we found consistent

  10. Sources and Reactivity of Terrestrial Organic Carbon to the Colville River Delta, Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Bianchi, T. S.; Rosenheim, B. E.

    2014-12-01

    Terrestrial particulate organic carbon (tPOC) delivery to nearshore deltaic regions is an important mechanism of OC storage and burial, and continental margins worldwide account for approximately 90% of the carbon burial in the ocean. Increasing warming in the Arctic is leading to an acceleration of the hydrologic cycle, warming of permafrost, and broad shifts in vegetation. All of these changes are likely to affect the delivery, reactivity, and burial of tPOC in nearshore Arctic regions, making the Arctic an ideal place to study the effects of climate change on tPOC delivery. However, to date, most studies of tPOC delivery from North America to the Arctic Ocean have focused on large Arctic rivers like the Mackenzie and Yukon, and a significant portion of those watersheds lie in sub-Arctic latitudes, meaning that their tPOC delivery is likely not uniquely representative of the high Arctic tundra. Here, we focus on tPOC delivery by the Colville River, the largest North American river with a watershed that does not include sub-Arctic latitudes. Sediment samples from the river delta and nearby Simpson's Lagoon were taken in August of 2010 and subsequently fractionated by density, in order to study the delivery of both discrete and sediment-sorbed tPOC. Samples were analyzed for stable carbon isotopes, bulk radiocarbon, terrestrial biomarkers (including lignin-phenols, and other CuO reaction products), and aquatic biomarkers (algal pigments), and additionally a subset of the samples were analyzed by ramped pyrolysis-14C. Results show that tPOC delivery near the river mouth is sourced from coastal plain tundra, with additional delivery of tPOC from peat released into the lagoon from the seaward limit of the tundra by coastal erosion. Ramped pyrolysis-14C analysis also shows a clear differentiation between tPOC delivered by the river and tPOC delivered by coastal retreat in the lagoon. Additionally, a significant portion of the OC released by the Colville River is

  11. Incubation behavior of Spectacled Eiders on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Grand, J.B.

    1999-01-01

    We studied incubation behavior of Spectacled Eiders (Somateria fischeri) on the Yukon-Kuskokwim Delta in 1996. We trapped 19 females on their nests and weighed them in early incubation and again at hatch. Average daily weight loss for incubating females was 16.6 ?? 1.0 g day-1, which resulted in a cumulative loss of 26% of body weight throughout incubation. Nest attendance was monitored for a portion of the incubation period using temperature sensing artificial eggs. Incubation constancy averaged 90 ?? 1%. Average recess length was 37.1 ?? 0.9 min, and nests cooled an average of 4.2 ?? 0.1??C during recesses. Recess frequency averaged 2.5 ?? 0.1 recesses day-1, and most recesses (70%) occurred between 10:00 and 22: 00. Incubation constancy varied among females, but was not related to changes in body weight or incubation period. There was no influence of ambient temperature on incubation recess length, however most recesses were taken during the warmest part of the day. We found considerable variation among females in patterns of daily incubation constancy, nest cooling, recess frequency, and recess length. It is not clear from our results what factors constrain incubation behavior of Spectacled Eiders, but we suggest that individual females respond to a complex suite of variables.

  12. A new indicator mineral methodology based on a generic Bi-Pb-Te-S mineral inclusion signature in detrital gold from porphyry and low/intermediate sulfidation epithermal environments in Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Chapman, R. J.; Allan, M. M.; Mortensen, J. K.; Wrighton, T. M.; Grimshaw, M. R.

    2017-12-01

    Porphyry-epithermal and orogenic gold are two of the most important styles of gold-bearing mineralization within orogenic belts. Populations of detrital gold resulting from bulk erosion of such regions may exhibit a compositional continuum wherein Ag, Cu, and Hg in the gold alloy may vary across the full range exhibited by natural gold. This paper describes a new methodology whereby orogenic and porphyry-epithermal gold may be distinguished according to the mineralogy of microscopic inclusions observed within detrital gold particles. A total of 1459 gold grains from hypogene, eluvial, and placer environments around calc-alkaline porphyry deposits in Yukon (Nucleus-Revenue, Casino, Sonora Gulch, and Cyprus-Klaza) have been characterized in terms of their alloy compositions (Au, Ag, Cu, and Hg) and their inclusion mineralogy. Despite differences in the evolution of the different magmatic hydrothermal systems, the gold exhibits a clear Bi-Pb-Te-S mineralogy in the inclusion suite, a signature which is either extremely weak or (most commonly) absent in both Yukon orogenic gold and gold from orogenic settings worldwide. Generic systematic compositional changes in ore mineralogy previously identified across the porphyry-epithermal transition have been identified in the corresponding inclusion suites observed in samples from Yukon. However, the Bi-Te association repeatedly observed in gold from the porphyry mineralization persists into the epithermal environment. Ranges of P-T-X conditions are replicated in the geological environments which define generic styles of mineralization. These parameters influence both gold alloy composition and ore mineralogy, of which inclusion suites are a manifestation. Consequently, we propose that this methodology approach can underpin a widely applicable indicator methodology based on detrital gold.

  13. Survival of breeding Pacific common eiders on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Wilson, H.M.; Flint, Paul L.; Moran, Christine L.; Powell, A.N.

    2007-01-01

    Populations of Pacific common eiders (Somateria mollissima v-nigrum) breeding in Alaska, USA, have declined markedly over the past 40 years. We studied survival of adult female Pacific common eiders using capture—recapture of nesting hens at 3 sites on the Yukon-Kuskokwim Delta (YKD), Alaska from 1994 to 2004. We used data consisting of 268 recapture events from 361 uniquely marked individuals to investigate temporal, geographic, and environmental variation in adult female survival. Our results suggest apparent annual survival of adult eiders from the YKD was high (0.892, SE = 0.022) and spatially and temporally invariant (σ2 = 0.005), a pattern consistent with other long-lived marine birds. Moreover, our results suggest adult survival may be functionally fixed for Pacific common eiders, and at the present, adult survival may be relatively unresponsive to environmental or management perturbations. Our data did not support hypothesized variation in survival relative to mortality factors such as predation on breeding grounds, physiologic costs of reproduction, and wintering conditions. Although changes in adult survival likely have a large potential effect on prospective population growth, our results suggest viable management actions aimed at increasing survival may be extremely limited.

  14. Yukon River King Salmon - Ichthyophonus Pilot Study

    USGS Publications Warehouse

    Kocan, R.M.; Hershberger, P.K.

    2001-01-01

    A method for non-lethal sampling of adult spawning Chinook salmon for Ichthyophonus was developed using known infected fish and live returning spawners. The method consisted of taking punch biopsies of skin and muscle and culturing the biopsy tissue in vitro. A 100% correlation was made between known infected fish and cultured biopsy tissue. 

  15. Alaska

    Atmospheric Science Data Center

    2014-05-15

    ... help to darken the room lights when viewing the image on a computer screen. The Yukon River is seen wending its way from upper left to ... NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed ...

  16. Statistical Aspects of Ice Gouging on the Alaskan Shelf of the Beaufort Sea,

    DTIC Science & Technology

    1983-09-01

    ici 1)N I’ao’ ofciv i1111 da t Cl t it:c) dcc iiiiik i onIII ol l % I IIouI ile as~ d a 1c’ iiici of ,ic dcli al\\2 Not1. I % .. ol I lOt ii title...Ccii hilial dclisl to fileicll of a p-ii peline lot a IX1 (X)-. Miid 10-\\Cat McUMr 1crOd .31 .... v STATISTICAL ASPECTS OF ICE GOUGING ON THE ALASKAN...dlata obtained hetceni 19-2 and -l aw etcnatr’’ib (I-). I Ilti, v, ’Icletriiutted 1 9,9 (ele cl iug 1 974) \\ -ere CL Ird in the pr~ mI. a~ctag ing tile

  17. Remarkable isotopic and trace element trends in potassic through sodic Cretaceous plutons of the Yukon-Koyukuk Basin, Alaska, and the nature of the lithosphere beneath the Koyukuk terrane

    USGS Publications Warehouse

    Arth, Joseph G.; Criss, Robert E.; Zmuda, Clara C.; Foley, Nora K.; Patton, W.W.; Miller, T.P.

    1989-01-01

    During the period from 110 to 80 m.y. ago, a 450-km-long magmatic belt was active along the northern margin of Yukon-Koyukuk basin and on eastern Seward Peninsula. The plutons intruded Upper Jurassic(?) and Lower Cretaceous volcanic arc rocks and Cretaceous sedimentary rocks in Yukon-Koyukuk basin and Proterozoic and lower Paleozoic continental rocks in Seward Peninsula. Within Yukon-Koyukuk basin, the plutons vary in composition from calc-alkalic plutons on the east to potassic and ultrapotassic alkalic plutons on the west. Plutons within Yukon-Koyukuk basin were analyzed for trace element and isotopic compositions in order to discern their origin and the nature of the underling lithosphere. Farthest to the east, the calc-alkalic rocks of Indian Mountain pluton are largely tonalite and sodic granodiorite, and have low Rb (average 82 ppm), high Sr (>600 ppm), high chondrite-normalized (cn) Ce/Yb (16–37), low δ18O (+6.5 to +7.1), low initial 87Sr/86Sr (SIR) (0.704), and high initial 143Nd/144Nd (NIR) (0.5126). These rocks resemble those modelled elsewhere as partial melts and subsequent fractionates of basaltic or gabbroic metaigneous rocks, and may be products of melting in the deeper parts of the Late Jurassic(?) and Early Cretaceous volcanic arc. Farthest to the west, the two ultrapotassic bodies of Selawik and Inland Lake are high in Cs (up to 93 ppm), Rb (up to 997 ppm), Sr, Ba, Th, and light rare earth elements, have high (Ce/Yb)cn (30, 27), moderate to low δ18O (+8.4, +6.9), high SIR (0.712, 0.710), and moderate NIR (0.5121–0.5122). These rocks resemble rocks of Australia and elsewhere that were modelled as melts of continental mantle that had been previously enriched in large cations. This mantle may be Paleozoic or older. The farthest west alkalic pluton of Selawik Hills is largely monzonite, quartz monzonite, and granite; has moderate Rb (average 284 ppm), high Sr (>600 ppm), high (Ce/Yb)cn (15–25), moderate δ18O (+8.3 to +8.6), high SIR (0.708

  18. Lessons learned in managing crowdsourced data in the Alaskan Arctic.

    NASA Astrophysics Data System (ADS)

    Mastracci, Diana

    2017-04-01

    There is perhaps no place in which the consequences of global climate change can be felt more acutely than the Arctic. However, due to lack of measurements at the high latitudes, validation processes are often problematic. Citizen science projects, co-designed together with Native communities at the interface of traditional knowledge and scientific research, could play a major role in climate change adaptation strategies by advancing knowledge of the Arctic system, strengthening inter-generational bonds and facilitating improved knowledge transfer. This presentation will present lessons learned from a pilot project in the Alaskan Arctic, in which innovative approaches were used to design climate change adaptation strategies to support young subsistence hunters in taking in-situ measurements whilst out on the sea-ice. Both the socio-cultural and hardware/software challenges presented in this presentation, could provide useful guidance for future programs that aim to integrate citizens' with scientific data in Arctic communities.

  19. Gold placers of the historical Fortymile River region, Alaska

    USGS Publications Warehouse

    Yeend, Warren E.

    1996-01-01

    The Fortymile River region in east-central Alaska has a long and colorful history as the site of the first major gold discovery in interior Alaska. Placer gold has been mined in the region nearly every year since its original discovery in 1886. Total gold production is approximately 500,000 troy ounces. Although many of the rich deposits have been mined, there still exist areas that contain gold. Areas of mined and unmined gold-bearing creek and terrace gravels are outlined on the accompanying geologic map. The early history of the Fortymile area centered on the small frontier settlement of Fortymile City located at the junction of the Fortymile and Yukon Rivers in Canadian territory. This was the supply and jumping-off point for prospectors who worked their way into Alaska up the Fortymile River and found gold on many of its tributaries. Hand mining, both underground and surface, using sluice boxes and (or) rockers were the earliest methods; later, hydraulicking, dredging, and draglining methods were used. More recently, bulldozers and elevated trammels have been used, as well as very portable floating suction dredges. The rich mining lore of the area is closely associated with events of the nearby world-famous Klondike District. Bedrock and placer geology and mining history of individual gold-rich creeks are herein updated. The Fortymile area, which is part of the Yukon-Tanana Upland, contains quartzite, schist, gneiss, amphibolite, marble, serpentinite, and granite overlain by basalt, sandstone, conglomerate, shale, tuff, and coal; overlying these rocks are several deposits of varying ages consisting of gold-bearing gravel and colluvium. The close spatial association of creeks containing placer gold and the gneiss, schist, amphibolite, and marble unit strongly suggests this metamorphic unit is the gold source. High terrace gravels record a time from the late Tertiary to early Pleistocene when the ancestral Fortymile River and its major tributaries, the North and

  20. Using smooth sheets to describe groundfish habitat in Alaskan waters, with specific application to two flatfishes

    USGS Publications Warehouse

    Zimmermann, Mark; Reid, Jane A.; Golden, Nadine

    2016-01-01

    In this analysis we demonstrate how preferred fish habitat can be predicted and mapped for juveniles of two Alaskan groundfish species – Pacific halibut (Hippoglossus stenolepis) and flathead sole (Hippoglossoides elassodon) – at five sites (Kiliuda Bay, Izhut Bay, Port Dick, Aialik Bay, and the Barren Islands) in the central Gulf of Alaska. The method involves using geographic information system (GIS) software to extract appropriate information from National Ocean Service (NOS) smooth sheets that are available from NGDC (the National Geophysical Data Center). These smooth sheets are highly detailed charts that include more soundings, substrates, shoreline and feature information than the more commonly-known navigational charts. By bringing the information from smooth sheets into a GIS, a variety of surfaces, such as depth, slope, rugosity and mean grain size were interpolated into raster surfaces. Other measurements such as site openness, shoreline length, proportion of bay that is near shore, areas of rocky reefs and kelp beds, water volumes, surface areas and vertical cross-sections were also made in order to quantify differences between the study sites. Proper GIS processing also allows linking the smooth sheets to other data sets, such as orthographic satellite photographs, topographic maps and precipitation estimates from which watersheds and runoff can be derived. This same methodology can be applied to larger areas, taking advantage of these free data sets to describe predicted groundfish essential fish habitat (EFH) in Alaskan waters.

  1. Using smooth sheets to describe groundfish habitat in Alaskan waters, with specific application to two flatfishes

    NASA Astrophysics Data System (ADS)

    Zimmermann, Mark; Reid, Jane A.; Golden, Nadine

    2016-10-01

    In this analysis we demonstrate how preferred fish habitat can be predicted and mapped for juveniles of two Alaskan groundfish species - Pacific halibut (Hippoglossus stenolepis) and flathead sole (Hippoglossoides elassodon) - at five sites (Kiliuda Bay, Izhut Bay, Port Dick, Aialik Bay, and the Barren Islands) in the central Gulf of Alaska. The method involves using geographic information system (GIS) software to extract appropriate information from National Ocean Service (NOS) smooth sheets that are available from NGDC (the National Geophysical Data Center). These smooth sheets are highly detailed charts that include more soundings, substrates, shoreline and feature information than the more commonly-known navigational charts. By bringing the information from smooth sheets into a GIS, a variety of surfaces, such as depth, slope, rugosity and mean grain size were interpolated into raster surfaces. Other measurements such as site openness, shoreline length, proportion of bay that is near shore, areas of rocky reefs and kelp beds, water volumes, surface areas and vertical cross-sections were also made in order to quantify differences between the study sites. Proper GIS processing also allows linking the smooth sheets to other data sets, such as orthographic satellite photographs, topographic maps and precipitation estimates from which watersheds and runoff can be derived. This same methodology can be applied to larger areas, taking advantage of these free data sets to describe predicted groundfish essential fish habitat (EFH) in Alaskan waters.

  2. Press releases, preliminary maps, and preliminary reports released by the Geologic Branch and Alaskan Branch between January 1, 1938 and January 1, 1945

    USGS Publications Warehouse

    Kent, Lois S.; Keroher, R.P.

    1945-01-01

    This pamphlet contains a complete list of all maps and reports issued by the Geologic Branch and Alaskan Branch of the Geological Survey whose release was announced by press notice during the period between January 1, 1938 and January 1, 1945. The Geologic Branch material was compiled by Lois S. Kent, and the Alaskan Branch material by R. P. Kerocher. It is expected that similar lists will be published annually hereafter. These reports and maps are the results of work carried out by Survey geologists on mineral deposits in the United States, Alaska, and Cuba during the war and the years immediately preceding the war. They were released in preliminary form as rapidly as possible in this period to avoid the delays necessarily attendant upon formal publication and to make the information contained in them promptly available to property owners and mine operators concerned with the production of strategic and critical mineral commodities.

  3. Estimation of Acoustic Particle Motion and Source Bearing Using a Drifting Hydrophone Array Near a River Current Turbine to Assess Disturbances to Fish

    NASA Astrophysics Data System (ADS)

    Murphy, Paul G.

    River hydrokinetic turbines may be an economical alternative to traditional energy sources for small communities on Alaskan rivers. However, there is concern that sound from these turbines could affect sockeye salmon (Oncorhynchus nerka), an important resource for small, subsistence based communities, commercial fisherman, and recreational anglers. The hearing sensitivity of sockeye salmon has not been quantified, but behavioral responses to sounds at frequencies less than a few hundred Hertz have been documented for Atlantic salmon (Salmo salar), and particle motion is thought to be the primary mode of stimulation. Methods of measuring acoustic particle motion are well-established, but have rarely been necessary in energetic areas, such as river and tidal current environments. In this study, the acoustic pressure in the vicinity of an operating river current turbine is measured using a freely drifting hydrophone array. Analysis of turbine sound reveals tones that vary in frequency and magnitude with turbine rotation rate, and that may sockeye salmon may sense. In addition to pressure, the vertical components of particle acceleration and velocity are estimated by calculating the finite difference of the pressure signals from the hydrophone array. A method of determining source bearing using an array of hydrophones is explored. The benefits and challenges of deploying drifting hydrophone arrays for marine renewable energy converter monitoring are discussed.

  4. Dwarfism in Alaskan malamutes: a disease resembling metaphyseal dysplasia in human beings.

    PubMed Central

    Sande, R. D.; Alexander, J. E.; Spencer, G. R.; Padgett, G. A.; Davis, W. C.

    1982-01-01

    In a study of 300 Alaskan Malamutes, dwarfism was shown to be an autosomal recessive inherited disease with complete penetrance that resulted in disturbed endochondral bone formation. Osseous growth disturbance was manifest at the metaphyses of tubular bones. Clinical and radiographic changes were very similar to those of rickets, although appositional bone formation rates were normal. Serum calcium, phosphorus, and alkaline phosphatase were within normal limits. Urinary excretion of calcium, phosphate, and amino acids were normal. Excess matrix was formed in the zone of cartilage cell proliferation, and the matrix persisted in the growth plate. Normal stresses resulted in microfractures in the metaphyses with subsequent interference of vascular penetration into the zone of degenerated cartilage cells. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:7065114

  5. Alaskan Superintendent Turnover: Is There a Correlation between Anticipated Turnover and the Organizational Culture of School Boards in the State of Alaska

    ERIC Educational Resources Information Center

    Herbert, David M. Q.

    2012-01-01

    The purpose of this study is to determine if a particular type of school board culture is predictive of Alaskan public school superintendents' intention to leave their positions. Cameron and Quinn's four types of organizational culture--hierarchy, market, clan, and adhocracy--serve as the model for the study, which surveyed Alaska's public school…

  6. Permafrost in the Yukon-Kuskokwim Delta, Alaska: a case for a holistic and integrated view of permafrost degradation

    NASA Astrophysics Data System (ADS)

    Herman-Mercer, N. M.; Schuster, P. F.; Laituri, M.; Elder, K.; Mutter, E. A.; Massey, M.; Matkin, E.; Toohey, R.

    2016-12-01

    The Yukon-Kuskokwim Delta (YKD) region of Alaska is a vast, marshy, lowland plain, underlain by discontinuous permafrost vulnerable to degradation. This region has been home to the Yup'ik and Cup'ik people, subsisting on local resources for centuries. Permafrost thaw in northern latitudes has become the focus of extensive scientific research in recent decades. However, the indigenous residents that live in these areas of degrading permafrost have been largely left out of scientific discussion and studies. More than fifty semi-structured interviews were conducted in four YKD communities. Interview questions were focused on the broad themes of seasonality of subsistence systems and observations of weather and landscape change. Responses revealed the myriad ways people interact with and observe permafrost in their day to day lives. For instance, permafrost is still utilized for food storage, people encounter permafrost when digging graves, and observe permafrost thaw in damage to their homes and other infrastructure in their communities. Yup'ik and Cup'ik residents have an intimate knowledge of the landscape owing to their subsistence based lifestyle and have reported observations of slumping ground, eroding river banks and coast lines as well as land that seems to be rising. Indigenous knowledge and observations complement broader scientific studies and should be used to inform permafrost research and assist in reconstructing historical baselines of permafrost distribution and active layer depth. Further, results of scientific research must be communicated to the people that may be impacted by present and future changes to permafrost that will likely result in changes to hydrologic flowpaths and ultimately ecosystem dynamics that may impact subsistence. Over millennia, northern indigenous communities have developed flexibility in resource harvesting and have exhibited adaptability to a variable and harsh environment. However, changes are being experienced at an

  7. A Report and Basic Proposal to Provide Alaskan Manpower Entry into the Pipeline and Related Construction Skills via Technical Training, Immediate and Intermediate.

    ERIC Educational Resources Information Center

    Bland, Laurel L.

    To make policy makers and others more aware of possibilities for utilizing Alaskan manpower, information has been gathered on the manpower demand to construct the proposed 800 mile Alaska oil pipeline and its supporting system. The recruitment and training of chronically unemployed or underemployed workers (largely Eskimos and Indians) is being…

  8. Tissue Distribution of Polychlorinated Biphenyls and Organochlorine Pesticides and Potential Toxicity to Alaskan Northern Fur Seals Assessed Using PCBs Congener Specific Mode of Action Schemes

    USDA-ARS?s Scientific Manuscript database

    The concentrations of 145 polychlorinated biphenyl (PCB) congeners were measured using gas chromatography-ion trap mass spectrometry in 8 different tissues (blubber, brain, heart, kidney, liver, lung, muscle, and reproductive tissues) of 10 Alaskan northern fur seals. The mean concentrations of bot...

  9. Late Holocene moisture balance variability in the southwest Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Anderson, Lesleigh; Abbott, Mark B.; Finney, Bruce P.; Burns, Stephen J.

    2007-01-01

    Analyses of sediment cores from Marcella Lake, a small, hydrologically closed lake in the semi-arid southwest Yukon, provides effective moisture information for the last ˜4500 years at century-scale resolution. Water chemistry and oxygen isotope analyses from lakes and precipitation in the region indicate that Marcella Lake is currently enriched in 18O by summer evaporation. Past lake water values are inferred from oxygen isotope analyses of sedimentary endogenic carbonate in the form of algal Charophyte stem encrustations. A record of the δ18O composition of mean annual precipitation at Jellybean Lake, a nearby evaporation-insensitive system, provides data of simultaneous δ18O variations related to decade-to-century scale shifts in Aleutian Low intensity/position. The difference between the two isotope records, Δδ, represents 18O-enrichment in Marcella Lake water caused by summer effective moisture conditions. Results indicate increased effective moisture between ˜3000 and 1200 cal BP and two marked shifts toward increased aridity at ˜1200 and between 300 and 200 cal BP. These prominent late Holocene changes in effective moisture occurred simultaneously with changes in Aleutian Low circulation patterns over the Gulf of Alaska indicated by Jellybean Lake. The reconstructed climate patterns are consistent with the topographically controlled climatic heterogeneity observed in the coastal mountains and interior valleys of the region today.

  10. Tracing pyrogenic carbon suspended in rivers on a global scale

    NASA Astrophysics Data System (ADS)

    Wiedemeier, Daniel B.; Haghipour, Negar; McIntyre, Cameron P.; Eglinton, Timothy I.; Schmidt, Michael W. I.

    2016-04-01

    Combustion-derived, pyrogenic carbon (PyC) is a persistent organic carbon fraction. Due to its aromatic and condensed nature (Wiedemeier et al., 2015), it is relatively resistant against chemical and biological degradation in the environment, leading to a comparatively slow turnover, which would support carbon sequestration. PyC is produced on large scales (hundreds of teragrams) in biomass burning events such as wildfires, and by combustion of fossil fuel in industry and traffic. PyC is an inherently terrestrial product and thus has predominantly been investigated in soils and the atmosphere. Much fewer studies are available about the subsequent transport of PyC to rivers and oceans. Recently, awareness has been rising about the mobility of PyC from terrestrial to marine systems and its fate in coastal and abyssal sediments was recognized (Mitra et al, 2013). It is therefore crucial to extend our knowledge about the PyC cycle by tracing PyC through all environmental compartments. By comparing its biogeochemical behavior and budgets to that of other forms of organic carbon, it will eventually be possible to elucidate PyC's total spatiotemporal contribution to carbon sequestration. In this study, we use a state-of-the-art PyC molecular marker method (Wiedemeier et al., 2013, Gierga et al., 2014) to trace quantity, quality as well as 13C and 14C signature of PyC in selected major river systems around the globe (Godavari, Yellow, Danube, Fraser, Mackenzie and Yukon river). Different size fractions of particulate suspended sediment are analyzed and compared across a north-south gradient. Previous studies suggested a distinct relationship between the 14C age of plant-derived suspended carbon and the latitude of the river system, indicating slower cycling of plant biomarkers in higher latitudes. We discuss this pattern with respect to PyC, its isotopic signature and quality and the resulting implications for the global carbon and PyC cycle. References Wiedemeier, D.B. et

  11. The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing

    USGS Publications Warehouse

    Rocha, Adrian V.; Loranty, Michael M.; Higuera, Phil E.; Mack, Michelle C.; Hu, Feng Sheng; Jones, Benjamin M.; Breen, Amy L.; Rastetter, Edward B.; Goetz, Scott J.; Shaver, Gus R.

    2012-01-01

    Recent large and frequent fires above the Alaskan arctic circle have forced a reassessment of the ecological and climatological importance of fire in arctic tundra ecosystems. Here we provide a general overview of the occurrence, distribution, and ecological and climate implications of Alaskan tundra fires over the past half-century using spatially explicit climate, fire, vegetation and remote sensing datasets for Alaska. Our analyses highlight the importance of vegetation biomass and environmental conditions in regulating tundra burning, and demonstrate that most tundra ecosystems are susceptible to burn, providing the environmental conditions are right. Over the past two decades, fire perimeters above the arctic circle have increased in size and importance, especially on the North Slope, indicating that future wildfire projections should account for fire regime changes in these regions. Remote sensing data and a literature review of thaw depths indicate that tundra fires have both positive and negative implications for climatic feedbacks including a decadal increase in albedo radiative forcing immediately after a fire, a stimulation of surface greenness and a persistent long-term (>10 year) increase in thaw depth. In order to address the future impact of tundra fires on climate, a better understanding of the control of tundra fire occurrence as well as the long-term impacts on ecosystem carbon cycling will be required.

  12. Effect of Tundra Fires on Stream Chemistry in Alaska's Yukon-Kuskokwim Delta

    NASA Astrophysics Data System (ADS)

    Jimmie, J. A.; Mann, P. J.; Schade, J. D.; Natali, S.; Fiske, G.; Holmes, R. M.

    2017-12-01

    Surface air temperatures in the Arctic have been increasing at approximately twice the global average, contributing to myriad changes including shifting vegetation, thawing permafrost, and altered surface and groundwater hydrology. Wildfire frequency and intensity has also been increasing, and in summer 2015, more area burned in the Yukon-Kuskowkwim Delta than in the previous 64 years combined. We investigated the impact of tundra fire on stream water chemistry, and by extension, on the movement of nutrients and organic matter between terrestrial and aquatic ecosystems. Using a high-resolution Digital Elevation Model, we characterized the contributing sub-watershed area at each of our stream water sampling locations and calculated the percent of each sub-watershed that was burned in summer 2015. We found that nitrate, ammonium, and phosphate concentrations increased with burn area in a watershed, indicating that terrestrial inputs of these constituents to aquatic systems increased following fire. Patterns were less striking for dissolved organic carbon and dissolved organic nitrogen, but there was a positive relationship between burn area and the concentration of these constituents as well. These results highlight the significant impact of tundra fires on terrestrial-aquatic linkages in the Arctic, and suggest that these impacts may increase in the future if fire in Arctic and boreal regions continues to become more common.

  13. Timing and Rate of Deglaciation of the MIS 2 Cordilleran Ice Sheet in Yukon Territory

    NASA Astrophysics Data System (ADS)

    Ward, B. C.; Bond, J. D.; Gosse, J. C.; Turner, D. G.

    2015-12-01

    The northern Cordilleran ice sheet (CIS) consisted of a series of quasi-independent ice lobes that coalesced during the last glacial maximum (LGM) to form a continuous carapace of precipitation limited ice over southern Yukon. Variations in effective precipitation to different source areas of these ice lobes have been used to explain disparities in glacier extents in marine oxygen isotope stages (MIS) 4 and 6. Deglaciation of the northern margin of the CIS and its rate of recession from the LGM are poorly understood. We use cosmogenic nuclide exposure dating (10Be and 36Cl) on groups of 3-4 glacial erratics to reconstruct the timing and rate of deglaciation. Our sampling concentrated on the St. Elias, Cassiar and Selwyn lobes, as well an independent glacier from the Ogilvie Mountains. Boulders sampled up-ice from terminal moraines show that the initiation of deglaciation varied regionally. 36Cl ages from the Ogilvie Mountains indicate that deglaciation initiated by 24.8 ka. Further south in the Selwyn Lobe, two sites separated by ~150 km returned ages of 15.2 and 16.1 ka. To the south-west, three boulders from the Cassiar Lobe are 13.6 ka. Rates of deglaciation are best constrained for the Cassiar Lobe with two transects along different flow lines. Multiple valley bottom samples in the mid-deglaciation setting at Whitehorse yielded ages of 12.0 ka, while one boulder from the adjacent ridge top 600 m above is 13.5 ka. In the accumulation zone, ice-free conditions occurred by 10.8 ka. The other transect has higher elevation samples in a mid-deglaciation setting in the Pelly Mountains that indicate deglaciation occurred by 13.0 ka. Samples taken from high elevation and valley bottom sites close to accumulation zones of the Cassiar Lobe yielded ages of 13.6 and 11.0 ka, respectively. These results provide a chronology for the style of deglaciation interpreted from regional mapping throughout Yukon: gradual initial retreat and thinning marked by moraines, followed by

  14. The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) FTS: Results From the 2012/13 Alaska Campaigns

    NASA Astrophysics Data System (ADS)

    kurosu, T. P.; Miller, C. E.; Dinardo, S.

    2013-12-01

    The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) is an aircraft-based Earth Venture 1 mission to study the carbon balance of the Alaskan Arctic ecosystem, with a particular focus on carbon release from melting permafrost. Operating from its base in Fairbanks, AK, the CARVE aircraft covers a range of principle flight paths in the Alaskan interior, the Yukon River valley, and northern Alaska coast around Barrow and Dead Horse. Flight paths are chosen to maximize ecosystem variability and and cover burn-recovery/regrowth sequences. CARVE observations cover the Arctic Spring/Summer/Fall seasons, with multiple flights per season and principle flight paths. Science operations started in 05/2012 and are currently envisaged to continue until 2015. The CARVE suite of instruments includes flask measurements and in situ gas analyzers for CO2, CH4 and CO observations, an active/passive L-band radar for surface conditions (freeze/thaw state), and a three-band polarizing Fourier Transform Spectrometer (FTS) for column measurements of CO2, CH4, CO, and interfering species (e.g., H2O). The FTS covers the spectral regions of 4,200-4,900 cm-1 (CH4, CO), 5,800-6,400 cm-1 (CO2), and 12,900-13,200 cm-1 (O2), with a spectral resolution of 0.2 cm-1. Aircraft-based FTS science observations in Alaska have been performed since 23-05-2012. First-version data products from all CARVE instruments derived from observations during the 2012 campaign were publicly released earlier in 2013. The FTS has performed well during flight conditions, particularly with respect to vibration damping. Outstanding challenges include the need for improved spectral and radiometric calibration, as well as compensating for low signal-to-noise spectra acquired under Alaskan flight conditions. We present results from FTS column observations of CO2, CH4, and CO, observed during the 2012 and 2013 campaigns, including preliminary comparisons of CARVE FTS measurements with satellite observations of CO2

  15. Identification of a haptoglobin-hemoglobin complex in the Alaskan Least Cisco (Coregonus sardinella).

    PubMed

    Wahl, S M; Boger, J K; Michael, V; Duffy, L K

    1992-01-01

    The hemoglobin and a hemoglobin binding protein have been characterized in the Arctic fish (Coregonus sardinella). The evolutionary significance of the hemoglobin and plasma protein differences between fish and mammals is still unresolved. Blood samples from the Alaskan Least Cisco were separated into plasma and hemoglobin fractions and the proteins in these fractions were analyzed both by alkaline agarose gel electrophoresis, by isolelectric focusing, and by capillary electrophoresis. Staining the plasma proteins gels with o-dianisidine revealed hemoglobin containing protein complexes. A hemoglobin-containing band was observed in hemolyzed plasma which did not migrate with free hemoglobin, and is believed to be hemoglobin-haptoglobin complex. Size exclusion chromatography further characterized the hemoglobin as disassociating freely into dimers, and hemoglobin-haptoglobin complex having a molecular weight greater then 200,000 daltons.

  16. Reconstruction of a high-resolution late holocene arctic paleoclimate record from Colville River delta sediments.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schreiner, Kathryn Melissa; Lowry, Thomas Stephen

    2013-10-01

    This work was partially supported by the Sandia National Laboratories, Laboratory Directed Research and Development (LDRD) fellowship program in conjunction with Texas A&M University (TAMU). The research described herein is the work of Kathryn M. Schreiner (Katie) and her advisor, Thomas S. Bianchi and represents a concise description of Katies dissertation that was submitted to the TAMU Office of Graduate Studies in May 2013 in partial fulfillment of her doctorate of philosophy degree. High Arctic permafrost soils contain a massive amount of organic carbon, accounting for twice as much carbon as what is currently stored as carbon dioxide in themore » atmosphere. However, with current warming trends this sink is in danger of thawing and potentially releasing large amounts of carbon as both carbon dioxide and methane into the atmosphere. It is difficult to make predictions about the future of this sink without knowing how it has reacted to past temperature and climate changes. This project investigated long term, fine scale particulate organic carbon (POC) delivery by the high-Arctic Colville River into Simpsons Lagoon in the near-shore Beaufort Sea. Modern POC was determined to be a mixture of three sources (riverine soils, coastal erosion, and marine). Downcore POC measurements were performed in a core close to the Colville River output and a core close to intense coastal erosion. Inputs of the three major sources were found to vary throughout the last two millennia, and in the Colville River core covary significantly with Alaskan temperature reconstructions.« less

  17. American Indians/Native Alaskans with Traumatic Brain Injury: Examining the Impairments of Traumatic Brain Injury, Disparities in Service Provision, and Employment Outcomes

    ERIC Educational Resources Information Center

    Whitfield, Harold Wayne; Lloyd, Rosalind

    2008-01-01

    The researchers analyzed data from fiscal year 2006 and found that American Indians/Native Alaskans (AI/NA) with traumatic brain injury experienced similar functional limitations at application as did non-AI/NA. Fewer funds were expended on purchased services for AI/NA than for non-AI/NA. The wages of AI/NA were equitable to those of non-AI/NA at…

  18. The Black Mountain tectonic zone--a reactivated northeast-trending crustal shear zone in the Yukon-Tanana Upland of east-central Alaska: Chapter D in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    USGS Publications Warehouse

    O'Neill, J. Michael; Day, Warren C.; Alienikoff, John N.; Saltus, Richard W.; Gough, Larry P.; Day, Warren C.

    2007-01-01

    The Black Mountain tectonic zone in the YukonTanana terrane of east-central Alaska is a belt of diverse northeast-trending geologic features that can been traced across Black Mountain in the southeast corner of the Big Delta 1°×3° degree quadrangle. Geologic mapping in the larger scale B1 quadrangle of the Big Delta quadrangle, in which Black Mountain is the principal physiographic feature, has revealed a continuous zone of normal and left-lateral strikeslip high-angle faults and shear zones, some of which have late Tertiary to Quaternary displacement histories. The tectonic zone includes complexly intruded wall rocks and intermingled apophyses of the contiguous mid-Cretaceous Goodpaster and Mount Harper granodioritic plutons, mafic to intermediate composite dike swarms, precious metal mineralization, early Tertiary volcanic activity and Quaternary fault scarps. These structures define a zone as much as 6 to 13 kilometers (km) wide and more than 40 km long that can be traced diagonally across the B1 quadrangle into the adjacent Eagle 1°×3° quadrangle to the east. Recurrent activity along the tectonic zone, from at least mid-Cretaceous to Quaternary, suggests the presence of a buried, fundamental tectonic feature beneath the zone that has influenced the tectonic development of this part of the Yukon-Tanana terrane. The tectonic zone, centered on Black Mountain, lies directly above a profound northeast-trending aeromagnetic anomaly between the Denali and Tintina fault systems. The anomaly separates moderate to strongly magnetic terrane on the northwest from a huge, weakly magnetic terrane on the southeast. The tectonic zone is parallel to the similarly oriented left-lateral, strike-slip Shaw Creek fault zone 85 km to the west.

  19. A RAB3GAP1 SINE Insertion in Alaskan Huskies with Polyneuropathy, Ocular Abnormalities, and Neuronal Vacuolation (POANV) Resembling Human Warburg Micro Syndrome 1 (WARBM1)

    PubMed Central

    Wiedmer, Michaela; Oevermann, Anna; Borer-Germann, Stephanie E.; Gorgas, Daniela; Shelton, G. Diane; Drögemüller, Michaela; Jagannathan, Vidhya; Henke, Diana; Leeb, Tosso

    2015-01-01

    We observed a hereditary phenotype in Alaskan Huskies that was characterized by polyneuropathy with ocular abnormalities and neuronal vacuolation (POANV). The affected dogs developed a progressive severe ataxia, which led to euthanasia between 8 and 16 months of age. The pedigrees were consistent with a monogenic autosomal recessive inheritance. We localized the causative genetic defect to a 4 Mb interval on chromosome 19 by a combined linkage and homozygosity mapping approach. Whole genome sequencing of one affected dog, an obligate carrier, and an unrelated control revealed a 218-bp SINE insertion into exon 7 of the RAB3GAP1 gene. The SINE insertion was perfectly associated with the disease phenotype in a cohort of 43 Alaskan Huskies, and it was absent from 541 control dogs of diverse other breeds. The SINE insertion induced aberrant splicing and led to a transcript with a greatly altered exon 7. RAB3GAP1 loss-of-function variants in humans cause Warburg Micro Syndrome 1 (WARBM1), which is characterized by additional developmental defects compared to canine POANV, whereas Rab3gap1-deficient mice have a much milder phenotype than either humans or dogs. Thus, the RAB3GAP1 mutant Alaskan Huskies provide an interesting intermediate phenotype that may help to better understand the function of RAB3GAP1 in development. Furthermore, the identification of the presumed causative genetic variant will enable genetic testing to avoid the nonintentional breeding of affected dogs. PMID:26596647

  20. Quantifying Fire Impact on Alaskan Tundra from Satellite Observations and Field Measurements

    NASA Astrophysics Data System (ADS)

    Loboda, T. V.; Chen, D.; He, J.; Jenkins, L. K.

    2017-12-01

    Wildfire is a major disturbance agent in Alaskan tundra. The frequency and extent of fire events obtained from paleo, management, and satellite records may yet underestimate the scope of tundra fire impact. Field measurements, collected within the NASA's ABoVE campaign, revealed unexpectedly shallow organic soils ( 15 cm) across all sampled sites of the Noatak valley with no significant difference between recently burned and unburned sites. In typical small and medium-sized tundra burns vegetation recovers rapidly and scars are not discernable in 30 m optical satellite imagery by the end of the first post-fire season. However, field observations indicate that vegetation and subsurface characteristics within fire scars of different ages vary across the landscape. In this study we develop linkages between fire-induced changes to tundra and satellite-based observations from optical, thermal, and microwave imagers to enable extrapolation of in-situ observations to cover the full extent of Alaskan tundra. Our results show that recent ( 30 years) fire history can be reconstructed from optical observations (R2 0.65, p<0.001) within a specific narrow temporal window or thermal signatures (R2 0.54, p < 0.001), in both cases controlled for slope and southern exposure. Using microwave SAR imagery fire history can be determined for 4 years post fire primarily due to increased soil moisture at burned sites. Field measurements suggest that the relatively quick SAR signal dissipation results from more even distribution of surface moisture through the soil column with increases in Active Layer Thickness (ALT). Similar to previous long-term field studies we find an increase in shrub fraction and shrub height within burns over time at the landscape scale; however, the strength and significance of the relationship between shrub fraction and time since fire is governed by burn severity with more severe burns predictably (p < 0.01) resulting in higher post-fire shrub cover. Although

  1. Assessing Seedling Recruitment in Retrogressive Thaw Slumps in the Alaskan Low Arctic

    NASA Astrophysics Data System (ADS)

    Huebner, D. C.; Bret-Harte, M. S.

    2016-12-01

    Thermal erosion of permafrost soils may promote shifts from moist acidic tussock tundra (MAT) to shrub tundra in the Alaskan Low Arctic. Tall birch and willow shrub thickets (>1 m) have been observed in stabilized retrogressive thaw slumps (RTS) caused by thermal erosion near lake margins. RTS contain unvegetated, sheltered microsites, which may revegetate through seedling recruitment. We assessed whether recruitment in RTS was greater than in undisturbed MAT by measuring increased seedling cover and seedbank viability. We expected that seedbanks would show post-RTS tradeoffs in quantity and quality, with young seedbanks containing fewer, mostly viable seeds whose viability would decrease as seeds accumulate after disturbance. We made pairwise comparisons of in-situ seedling counts, seedbank viability (percent germination), and seed density (seeds m-2) of soil seedbanks across a chronosequence of RTS and nearby undisturbed MAT (n = 8 sample areas) at two sites near Toolik Lake, Alaska. Both RTS chronosequences were aged in a previous study through shrub ring counts and radiocarbon dated peat. RTS included young (1-10 years after disturbance), middle-aged (10-29 years) and old (> 30 years) sites. Undisturbed MAT areas were not aged but were likely undisturbed by RTS for > 300 years. We found 6 to 40 times more in-situ seedlings in younger RTS than in older RTS, and no seedlings in undisturbed MAT. Younger RTS had more willow and birch seedlings than older RTS. Higher in-situ seedling counts were correlated with deeper thaw depths, more bare soil, and decreased elevation, which suggested sheltering effects. Seedbank viability was unrelated to seedbank size or in-situ counts. Seedbank size increased with age at only one RTS site with no difference in percent germination. At the other site, percent germination decreased with age, but seedbank size was not different. Willow and birch germination was 1-2% overall. Site differences in seedbank size, viability, and species

  2. Prevalence and persistence of antibodies to herpes viruses, Chlamydia pneumoniae and Helicobacter pylori in Alaskan Eskimos: the GOCADAN Study.

    PubMed

    Zhu, J; Davidson, M; Leinonen, M; Saikku, P; Gaydos, C A; Canos, D A; Gutman, K A; Howard, B V; Epstein, S E

    2006-02-01

    The prevalence and persistence of antibodies against cytomegalovirus (CMV), herpes simplex virus types 1 (HSV1) and 2 (HSV2), Helicobacter pylori and Chlamydia pneumoniae were determined in Alaskan Eskimos. The study included 610 individuals (mean age 43 +/- 15 years; 45% males) participating in the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) study. Archived serum samples and those collected during the GOCADAN study were analysed for antibodies against the above pathogens by ELISA. The current prevalence of antibody seropositivity was 94% to CMV, 90% to HSV1, 38% to HSV2, 80% to H. pylori, and 42% to C. pneumoniae. The persistence of antibodies (in both archived and current samples) against CMV, HSV1 and H. pylori was high (83%, 84% and 67%, respectively) compared with those against HSV2 (26%) and C. pneumoniae (29%). Moreover, the seroconversion rates to these organisms were low. Most individuals acquired CMV, HSV1 and H. pylori antibodies by the age of 24 years (94%, 90% and 72%, respectively), and >50% carried HSV2 and C. pneumoniae antibodies by the age of 45 years. There were gender differences in antibody seropositivity rates. Over 70% of individuals had antibodies to at least three of the five pathogens tested. The study demonstrated the high prevalence and lifelong persistence of multiple antibodies, suggesting chronic infections among Alaskan Eskimos.

  3. 76 FR 304 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Red Knot...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ...). Juveniles resemble non-breeding adults, except that the feathers of the scapulars and wing coverts of... stopover sites are Grays Harbor and Willapa Bay in Washington, and Yukon-Kuskokwim Delta and Copper River Delta in Alaska (Isleib 1979, p. 128; Gill and Handel 1990, p. 712; Page et al. 1999, p. 467). Smaller...

  4. Building research capacity with members of underserved American Indian/Alaskan Native communities: training in research ethics and the protection of human subjects.

    PubMed

    Jetter, Karen M; Yarborough, Mark; Cassady, Diana L; Styne, Dennis M

    2015-05-01

    To develop a research ethics training course for American Indian/Alaskan Native health clinic staff and community researchers who would be conducting human subjects research. Community-based participatory research methods were used in facilitated discussions of research ethics centered around topics included in the Collaborative Institutional Training Initiative research ethics course. The community-based participatory research approach allowed all partners to jointly develop a research ethics training program that was relevant for American Indian/Alaskan Native communities. All community and clinic partners were able to pass the Collaborative Institutional Training Initiative course they were required to pass so that they could be certified to conduct research with human subjects on federally funded projects. In addition, the training sessions provided a foundation for increased community oversight of research. By using a collaborative process to engage community partners in research ethics discussions, rather than either an asynchronous online or a lecture/presentation format, resulted in significant mutual learning about research ethics and community concerns about research. This approach requires university researchers to invest time in learning about the communities in which they will be working prior to the training. © 2014 Society for Public Health Education.

  5. Survival of Western Sandpiper broods on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Ruthrauff, D.R.; McCaffery, B.J.

    2005-01-01

    The rate of chick growth in high-latitude breeding shorebirds is rapid, but little is known about the effect of chick mass, growth, and brood movements on subsequent brood survival. To address these topics, we monitored chick growth patterns, daily brood movements, and survival of Western Sandpipers (Calidris mauri) on the Yukon-Kuskokwim Delta, Alaska. We assessed the effect of chick age, mass, and hatch date on brood survival using Program MARK. We mapped brood locations daily, and compared brood movement patterns between successful and unsuccessful broods. Younger chicks survived at lower rates and moved shorter distances than older chicks. The overall probability of one or more chicks from a brood surviving to 15 days of age was 0.73 ± 0.05 SE. Brood survival declined seasonally, and broods with heavier chicks survived at higher rates than those with lighter chicks. On average, successful broods fledged 1.7 ± 0.1 SE chicks. Rate of chick growth was intermediate between those of high arctic and temperate-breeding shorebirds, and chick mass at hatching declined seasonally. Western Sandpiper brood survival was lowest when chicks were young, spatially clumped, and unable to maintain homeothermy, probably because young chicks were more vulnerable to both complete depredation events and extreme weather. Our data suggest that larger, older chicks are able to avoid predators by being spatially dispersed and highly mobile; thermal independence, achieved after approximately day five, enables chicks to better endure prolonged periods of cold and low food availability.

  6. Glaucous gull predation of goslings on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Bowman, Timothy D.; Stehn, R.A.; Scribner, K.T.

    2004-01-01

    Glaucous Gulls (Larus hyperboreus) nesting on the Yukon-Kuskokwim (Y-K) Delta frequently prey on juvenile waterfowl. We collected 434 Glaucous Gulls from late June to early August 1994 to examine diet. Identification of undigested prey tissue, based on DNA microsatellite loci, showed three species of goslings in gull stomachs: Emperor Goose (Chen canagica), White-fronted Goose (Anser albifrons), and Cackling Canada Goose (Branta canadensis minima). Gulls that nested inland and were collected > 1.6 km from the coast accounted for approximately 70% of the total gull predation on Emperor and Canada Geese, and 96% on White-fronted Geese. Our stratified sample of gull stomachs and aerial survey estimates of population size and distribution of gulls and juvenile geese enabled extrapolation of species-specific predation rates to the entire Y-K Delta. We estimated that a minimum of 21 000 Emperor Goose, 34 000 Canada Goose, and 16 000 White-fronted Goose goslings were consumed by 12 600 Glaucous Gulls during the brood-rearing period on the Y-K Delta in 1994. Minimum estimated take by gulls represented 33% of Cackling Canada Goose, 47% of Emperor Goose, and 39% of White-fronted Goose eggs estimated to have hatched in the same area as gull collections. Gulls selected the three species of geese approximately in proportion to their abundance. Although gull predation caused significant gosling mortality, its role in regulating goose populations on Y-K Delta remains unresolved.

  7. Thermal and hydrological observations near Twelvemile Lake in discontinuous permafrost, Yukon Flats, interior Alaska, September 2010-August 2011

    USGS Publications Warehouse

    Jepsen, Steven M.; Koch, Joshua C.; Rose, Joshua R.; Voss, Clifford I.; Walvoord, Michelle Ann

    2012-01-01

    A series of ground-based observations were made between September 2010 and August 2011 near Twelvemile Lake, 19 kilometers southwest of Fort Yukon, Alaska, for use in ongoing hydrological analyses of watersheds in this region of discontinuous permafrost. Measurements include depth to ground ice, depth to water table, soil texture, soil moisture, soil temperature, and water pressure above the permafrost table. In the drained basin of subsiding Twelvemile Lake, we generally find an absence of newly formed permafrost and an undetectable slope of the water table; however, a sloping water table was observed in the low-lying channels extending into and away from the lake watershed. Datasets for these observations are summarized in this report and can be accessed by clicking on the links in each section or from the Downloads folder of the report Web page.

  8. Distribution of clay minerals on the Alaskan margin near Barrow Canyon revealed by Diffuse Spectral Reflectance measurements

    NASA Astrophysics Data System (ADS)

    Orsburn, C.; Ortiz, J. D.; Polyak, L.; Grebmeier, J. M.; Darby, D.

    2007-12-01

    Sediment clay mineral assemblages provide an excellent means of assessing the provenance of Arctic sediment due to the variety of sediment transport mechanisms at work and the existence of distinct weathering sources from differing bedrock geology. During HOTRAX Leg 1 aboard the USCG Ice breaker Healy (cruise HLY0501), we collected jumbo piston cores on the Alaskan margin near Barrow Canyon which provide detailed Holocene sedimentary records. Measurements of Diffuse Spectral Reflectance (DSR) were collected at 1cm resolution from the split surface of the cores using a Minolta CM-2600d UV/VIS spectrophotometer (400-700nm wavelength range; 10nm resolution; 3mm spot size). To interpret the resulting downcore records, we present a preliminary study using 28 coretop sediment samples collected by the Shelf-Basin Interaction program in 2004 arrayed in four transects across the shelf near Barrow Canyon. The samples were analyzed using an ASD Labspec Pro FR UV/VIS/NIR spectrometer (250-2500nm wavelength range, 2-10nm resolution; 20mm spot size). Our results indicate that the measurements from the two instruments are offset by constant factors, but can be easily compared. To estimate the clay mineralogy of the cores, we decomposed the matrix of DSR measurements from the coretop and downcore samples using principle component analysis and compared the resulting factor score patterns with mineral diffuse spectral reflectance signatures from known samples measured in our lab or available from version 5 of the USGS Digital Spectral Library. The three leading modes extracted by principle component analysis of the downcore samples are applicable to the coretops. We infer that the first principle component mode relates to smectite, the second to chlorite, and the third to a mixture of illite and goethite (herein referred to as illite - goethite). The geographic and bathymetric trends in the coretop data indicate that (1) the smectite and illite - goethite components both increase

  9. Quantifying soil carbon accumulation in Alaskan terrestrial ecosystems during the last 15 000 years

    DOE PAGES

    Wang, Sirui; Zhuang, Qianlai; Yu, Zicheng

    2016-11-25

    Northern high latitudes contain large amounts of soil organic carbon (SOC), of which Alaskan terrestrial ecosystems account for a substantial proportion. In this study, the SOC accumulation in Alaskan terrestrial ecosystems over the last 15 000 years was simulated using a process-based biogeochemistry model for both peatland and non-peatland ecosystems. Comparable with the previous estimates of 25–70 Pg C in peatland and 13–22 Pg C in non-peatland soils within 1 m depth in Alaska using peat-core data, our model estimated a total SOC of 36–63 Pg C at present, including 27–48 Pg C in peatland soils and 9–15 Pg C in non-peatland soils. Current vegetation stored 2.5–3.7 Pg C in Alaska, with 0.3–0.6 Pg C in peatlandsmore » and 2.2–3.1 Pg C in non-peatlands. The simulated average rate of peat C accumulation was 2.3 Tg C yr −1, with a peak value of 5.1 Tg C yr −1 during the Holocene Thermal Maximum (HTM) in the early Holocene, 4-fold higher than the average rate of 1.4 Tg C yr −1 over the rest of the Holocene. The SOC accumulation slowed down, or even ceased, during the neoglacial climate cooling after the mid-Holocene, but increased again in the 20th century. The model-estimated peat depths ranged from 1.1 to 2.7 m, similar to the field-based estimate of 2.29 m for the region. We found that the changes in vegetation and their distributions were the main factors in determining the spatial variations of SOC accumulation during different time periods. Warmer summer temperature and stronger radiation seasonality, along with higher precipitation in the HTM and the 20th century, might have resulted in the extensive peatland expansion and carbon accumulation.« less

  10. Quantifying soil carbon accumulation in Alaskan terrestrial ecosystems during the last 15 000 years

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Sirui; Zhuang, Qianlai; Yu, Zicheng

    Northern high latitudes contain large amounts of soil organic carbon (SOC), of which Alaskan terrestrial ecosystems account for a substantial proportion. In this study, the SOC accumulation in Alaskan terrestrial ecosystems over the last 15 000 years was simulated using a process-based biogeochemistry model for both peatland and non-peatland ecosystems. Comparable with the previous estimates of 25–70 Pg C in peatland and 13–22 Pg C in non-peatland soils within 1 m depth in Alaska using peat-core data, our model estimated a total SOC of 36–63 Pg C at present, including 27–48 Pg C in peatland soils and 9–15 Pg C in non-peatland soils. Current vegetation stored 2.5–3.7 Pg C in Alaska, with 0.3–0.6 Pg C in peatlandsmore » and 2.2–3.1 Pg C in non-peatlands. The simulated average rate of peat C accumulation was 2.3 Tg C yr −1, with a peak value of 5.1 Tg C yr −1 during the Holocene Thermal Maximum (HTM) in the early Holocene, 4-fold higher than the average rate of 1.4 Tg C yr −1 over the rest of the Holocene. The SOC accumulation slowed down, or even ceased, during the neoglacial climate cooling after the mid-Holocene, but increased again in the 20th century. The model-estimated peat depths ranged from 1.1 to 2.7 m, similar to the field-based estimate of 2.29 m for the region. We found that the changes in vegetation and their distributions were the main factors in determining the spatial variations of SOC accumulation during different time periods. Warmer summer temperature and stronger radiation seasonality, along with higher precipitation in the HTM and the 20th century, might have resulted in the extensive peatland expansion and carbon accumulation.« less

  11. Wearing surface testing and screening : Yukon River Bridge.

    DOT National Transportation Integrated Search

    2015-09-01

    There is a demand and a need for cheaper and alternative surface coverings in environments with high temperature fluctuations. Our : design for an alternative surface covering involves a basic two-part component epoxy with the addition of a solvent. ...

  12. Transcriptomic and metabolomic analysis of Yukon Thellungiella plants grown in cabinets and their natural habitat show phenotypic plasticity

    PubMed Central

    2012-01-01

    Background Thellungiella salsuginea is an important model plant due to its natural tolerance to abiotic stresses including salt, cold, and water deficits. Microarray and metabolite profiling have shown that Thellungiella undergoes stress-responsive changes in transcript and organic solute abundance when grown under controlled environmental conditions. However, few reports assess the capacity of plants to display stress-responsive traits in natural habitats where concurrent stresses are the norm. Results To determine whether stress-responsive changes observed in cabinet-grown plants are recapitulated in the field, we analyzed leaf transcript and metabolic profiles of Thellungiella growing in its native Yukon habitat during two years of contrasting meteorological conditions. We found 673 genes showing differential expression between field and unstressed, chamber-grown plants. There were comparatively few overlaps between genes expressed under field and cabinet treatment-specific conditions. Only 20 of 99 drought-responsive genes were expressed both in the field during a year of low precipitation and in plants subjected to drought treatments in cabinets. There was also a general pattern of lower abundance among metabolites found in field plants relative to control or stress-treated plants in growth cabinets. Nutrient availability may explain some of the observed differences. For example, proline accumulated to high levels in cold and salt-stressed cabinet-grown plants but proline content was, by comparison, negligible in plants at a saline Yukon field site. We show that proline accumulated in a stress-responsive manner in Thellungiella plants salinized in growth cabinets and in salt-stressed seedlings when nitrogen was provided at 1.0 mM. In seedlings grown on 0.1 mM nitrogen medium, the proline content was low while carbohydrates increased. The relatively higher content of sugar-like compounds in field plants and seedlings on low nitrogen media suggests that

  13. Creating a Strong, Healthy Community: Ella B. Vernetti School, Koyukuk. Case Study.

    ERIC Educational Resources Information Center

    Leonard, Beth

    As part of a larger study of systemic educational reform in rural Alaska, this case study examines implementation of the Alaska Onward to Excellence (AOTE) process in Koyukuk, a small Athabascan village on the Yukon River in western interior Alaska. The village has a K-10 school with an enrollment of 19-41 students during the study period. A…

  14. Yesterday Still Lives...Our Native People Remember Alaska.

    ERIC Educational Resources Information Center

    DeMarco, Pat, Ed.; And Others

    In the summer of 1978, seven teenagers and several staff members from the Fairbanks Native Association-Johnson O'Malley program set out to record some of Alaska's past by interviewing a number of older Alaska Natives and writing their biographical sketches. Some of the students spent a week along the Yukon River taping and photographing people;…

  15. Alaska's forest resource.

    Treesearch

    O. Keith Hutchison

    1968-01-01

    Alaska's romantic past includes the magnetic lure of gold; the mad stampede to strike it rich; success and heartbreak; men and animals battling snow, ice, spring breakup, insects, and loneliness; dog teams at work and on desperate missions; river steamers battling the Yukon; bush pilots performing miraculous flights; and hordes of salmon taken by traps and seine...

  16. An assessment of the risk of foreign animal disease introduction into the United States of America through garbage from Alaskan cruise ships.

    PubMed

    McElvaine, M D; McDowell, R M; Fite, R W; Miller, L

    1993-12-01

    The United States Department of Agriculture, Animal and Plant Health Inspection Service (USDA-APHIS) has been exploring methods of quantitative risk assessment to support decision-making, provide risk management options and identify research needs. With current changes in world trade, regulatory decisions must have a scientific basis which is transparent, consistent, documentable and defensible. These quantitative risk assessment methods are described in an accompanying paper in this issue. In the present article, the authors provide an illustration by presenting an application of these methods. Prior to proposing changes in regulations, USDA officials requested an assessment of the risk of introduction of foreign animal disease to the United States of America through garbage from Alaskan cruise ships. The risk assessment team used a combination of quantitative and qualitative methods to evaluate this question. Quantitative risk assessment methods were used to estimate the amount of materials of foreign origin being sent to Alaskan landfills. This application of quantitative risk assessment illustrates the flexibility of the methods in addressing specific questions. By applying these methods, specific areas were identified where more scientific information and research were needed. Even with limited information, the risk assessment provided APHIS management with a scientific basis for a regulatory decision.

  17. Beringian sub-refugia revealed in blackfish (Dallia): implications for understanding the effects of Pleistocene glaciations on Beringian taxa and other Arctic aquatic fauna.

    PubMed

    Campbell, Matthew A; Takebayashi, Naoki; López, J Andrés

    2015-07-19

    Pleistocene climatic instability had profound and diverse effects on the distribution and abundance of Arctic organisms revealed by variation in phylogeographic patterns documented in extant Arctic populations. To better understand the effects of geography and paleoclimate on Beringian freshwater fishes, we examined genetic variability in the genus Dallia (blackfish: Esociformes: Esocidae). The genus Dallia groups between one and three nominal species of small, cold- and hypoxia-tolerant freshwater fishes restricted entirely in distribution to Beringia from the Yukon River basin near Fairbanks, Alaska westward including the Kuskokwim River basin and low-lying areas of Western Alaska to the Amguema River on the north side of the Chukotka Peninsula and Mechigmen Bay on the south side of the Chukotka Peninsula. The genus has a non-continuous distribution divided by the Bering Strait and the Brooks Range. We examined the distribution of genetic variation across this range to determine the number and location of potential sub-refugia within the greater Beringian refugium as well as the roles of the Bering land bridge, Brooks Range, and large rivers within Beringia in shaping the current distribution of populations of Dallia. Our analyses were based on DNA sequence data from two nuclear gene introns (S7 and RAG1) and two mitochondrial genome fragments from nineteen sampling locations. These data were examined under genetic clustering and coalescent frameworks to identify sub-refugia within the greater Beringia refugium and to infer the demographic history of different populations of Dallia. We identified up to five distinct genetic clusters of Dallia. Four of these genetic clusters are present in Alaska: (1) Arctic Coastal Plain genetic cluster found north of the Brooks Range, (2) interior Alaska genetic cluster placed in upstream locations in the Kuskokwim and Yukon river basins, (3) a genetic cluster found on the Seward Peninsula, and (4) a coastal Alaska genetic

  18. Long-wave Irradiance Measurement and Modeling during Snowmelt, a Case Study in the Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Sicart, J.; Essery, R.; Pomeroy, J.

    2004-12-01

    At high latitudes, long-wave radiation emitted by the atmosphere and solar radiation can provide similar amounts of energy for snowmelt due to the low solar elevation and the high albedo of snow. This paper investigates temporal and spatial variations of long-wave irradiance at the snow surface in an open sub-Arctic environment. Measurements were conducted in the Wolf Creek Research Basin, Yukon Territory, Canada (60°36'N, 134°57'W) during the springs of 2002, 2003 and 2004. The main causes of temporal variability are air temperature and cloud cover, especially in the beginning of the melting period when the atmosphere is still cold. Spatial variability was investigated through a sensitivity study to sky view factors and to temperatures of surrounding terrain. The formula of Brutsaert gives a useful estimation of the clear-sky irradiance at hourly time steps. Emission by clouds was parameterized at the daily time scale from the atmospheric attenuation of solar radiation. The inclusion of air temperature variability does not much improve the calculation of cloud emission.

  19. Reconstruction of fire history of the Yukon-Kuskokwim Delta, Alaska

    NASA Astrophysics Data System (ADS)

    Sae-lim, J.; Mann, P. J.; Russell, J. M.; Natali, S.; Vachula, R. S.; Schade, J. D.; Holmes, R. M.

    2017-12-01

    Wildfire is an important disturbance in Arctic ecosystems and can cause abrupt perturbations in global carbon cycling and atmospheric chemistry. Over the next few decades, arctic fire frequency, intensity and extent is projected to increase due to anthropogenic climate change, as regional air temperatures are increasing at more than twice the global average. In order to more accurately predict the anthropogenic impacts of climate change on tundra fire regimes, it is critical to have detailed knowledge of the natural frequency and extent of past wildfires. However, reliable historical records only extend back a few hundred years, whereas climatic shifts have affected fire regimes for thousands of years. In this work we analyzed a lake sediment core collected from the Yukon-Kuskokwim (YK) Delta, Alaska, a region that has recently experienced fire and is predicted to see increasing fire frequency in the near future. Our primary lake site is situated adjacent to recent burned areas, providing a `calibration' point and also attesting to the sensitivity of the sites. We used charcoal counts alongside geochemical measurements (C:N, 13C, 15N, 210Pb, X-ray fluorescence analyses of elemental chemistry) to reconstruct past fire history and ecosystem responses during the late Holocene. Average C (%C) and N concentrations (%N) in the core were 8.10 ±0.74% and 0.48 ±0.05%, resulting in C:N ratios of 16.80 ±0.74. The values are generally stable, with no obvious trend in C, N or C:N with depth; however, fluctuations in sediment composition in other nearby lake sediment cores possibly suggests shifts in lake conditions (oxic, anoxic) over time that might result from paleofires. This study provides a baseline for estimated fire return intervals in the YK Delta that will support more accurate projections of tundra fire frequencies under a changing climate.

  20. Google's Geo Education Outreach: Results and Discussion of Outreach Trip to Alaskan High Schools.

    NASA Astrophysics Data System (ADS)

    Kolb, E. J.; Bailey, J.; Bishop, A.; Cain, J.; Goddard, M.; Hurowitz, K.; Kennedy, K.; Ornduff, T.; Sfraga, M.; Wernecke, J.

    2008-12-01

    The focus of Google's Geo Education outreach efforts (http://www.google.com/educators/geo.html) is on helping primary, secondary, and post-secondary educators incorporate Google Earth and Sky, Google Maps, and SketchUp into their classroom lessons. In partnership with the University of Alaska, our Geo Education team members visited several remote Alaskan high schools during a one-week period in September. At each school, we led several 40-minute hands-on learning sessions in which Google products were used by the students to investigate local geologic and environmental processes. For the teachers, we provided several resources including follow-on lesson plans, example KML-based lessons, useful URL's, and website resources that multiple users can contribute to. This talk will highlight results of the trip and discuss how educators can access and use Google's Geo Education resources.